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Diffstat (limited to 'Documentation/filesystems/proc.rst')
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1 files changed, 389 insertions, 277 deletions
diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst index 38b606991065..104c6d047d9b 100644 --- a/Documentation/filesystems/proc.rst +++ b/Documentation/filesystems/proc.rst @@ -47,10 +47,13 @@ fixes/update part 1.1 Stefani Seibold <stefani@seibold.net> June 9 2009 3.10 /proc/<pid>/timerslack_ns - Task timerslack value 3.11 /proc/<pid>/patch_state - Livepatch patch operation state 3.12 /proc/<pid>/arch_status - Task architecture specific information + 3.13 /proc/<pid>/fd - List of symlinks to open files 4 Configuring procfs 4.1 Mount options + 5 Filesystem behavior + Preface ======= @@ -82,7 +85,7 @@ contact Bodo Bauer at bb@ricochet.net. We'll be happy to add them to this document. The latest version of this document is available online at -http://tldp.org/LDP/Linux-Filesystem-Hierarchy/html/proc.html +https://www.kernel.org/doc/html/latest/filesystems/proc.html If the above direction does not works for you, you could try the kernel mailing list at linux-kernel@vger.kernel.org and/or try to reach me at @@ -121,10 +124,10 @@ show you how you can use /proc/sys to change settings. The directory /proc contains (among other things) one subdirectory for each process running on the system, which is named after the process ID (PID). -The link self points to the process reading the file system. Each process +The link 'self' points to the process reading the file system. Each process subdirectory has the entries listed in Table 1-1. -Note that an open a file descriptor to /proc/<pid> or to any of its +Note that an open file descriptor to /proc/<pid> or to any of its contained files or subdirectories does not prevent <pid> being reused for some other process in the event that <pid> exits. Operations on open /proc/<pid> file descriptors corresponding to dead processes @@ -176,6 +179,7 @@ read the file /proc/PID/status:: Gid: 100 100 100 100 FDSize: 256 Groups: 100 14 16 + Kthread: 0 VmPeak: 5004 kB VmSize: 5004 kB VmLck: 0 kB @@ -208,6 +212,7 @@ read the file /proc/PID/status:: NoNewPrivs: 0 Seccomp: 0 Speculation_Store_Bypass: thread vulnerable + SpeculationIndirectBranch: conditional enabled voluntary_ctxt_switches: 0 nonvoluntary_ctxt_switches: 1 @@ -218,7 +223,7 @@ file /proc/PID/status. It fields are described in table 1-2. The statm file contains more detailed information about the process memory usage. Its seven fields are explained in Table 1-3. The stat file -contains details information about the process itself. Its fields are +contains detailed information about the process itself. Its fields are explained in Table 1-4. (for SMP CONFIG users) @@ -228,7 +233,7 @@ asynchronous manner and the value may not be very precise. To see a precise snapshot of a moment, you can see /proc/<pid>/smaps file and scan page table. It's slow but very precise. -.. table:: Table 1-2: Contents of the status files (as of 4.19) +.. table:: Table 1-2: Contents of the status fields (as of 4.19) ========================== =================================================== Field Content @@ -242,7 +247,8 @@ It's slow but very precise. Ngid NUMA group ID (0 if none) Pid process id PPid process id of the parent process - TracerPid PID of process tracing this process (0 if not) + TracerPid PID of process tracing this process (0 if not, or + the tracer is outside of the current pid namespace) Uid Real, effective, saved set, and file system UIDs Gid Real, effective, saved set, and file system GIDs FDSize number of file descriptor slots currently allocated @@ -251,6 +257,7 @@ It's slow but very precise. NSpid descendant namespace process ID hierarchy NSpgid descendant namespace process group ID hierarchy NSsid descendant namespace session ID hierarchy + Kthread kernel thread flag, 1 is yes, 0 is no VmPeak peak virtual memory size VmSize total program size VmLck locked memory size @@ -290,6 +297,7 @@ It's slow but very precise. NoNewPrivs no_new_privs, like prctl(PR_GET_NO_NEW_PRIV, ...) Seccomp seccomp mode, like prctl(PR_GET_SECCOMP, ...) Speculation_Store_Bypass speculative store bypass mitigation status + SpeculationIndirectBranch indirect branch speculation mode Cpus_allowed mask of CPUs on which this process may run Cpus_allowed_list Same as previous, but in "list format" Mems_allowed mask of memory nodes allowed to this process @@ -299,7 +307,7 @@ It's slow but very precise. ========================== =================================================== -.. table:: Table 1-3: Contents of the statm files (as of 2.6.8-rc3) +.. table:: Table 1-3: Contents of the statm fields (as of 2.6.8-rc3) ======== =============================== ============================== Field Content @@ -317,7 +325,7 @@ It's slow but very precise. ======== =============================== ============================== -.. table:: Table 1-4: Contents of the stat files (as of 2.6.30-rc7) +.. table:: Table 1-4: Contents of the stat fields (as of 2.6.30-rc7) ============= =============================================================== Field Content @@ -422,12 +430,16 @@ with the memory region, as the case would be with BSS (uninitialized data). The "pathname" shows the name associated file for this mapping. If the mapping is not associated with a file: - ======= ==================================== + =================== =========================================== [heap] the heap of the program [stack] the stack of the main process [vdso] the "virtual dynamic shared object", the kernel system call handler - ======= ==================================== + [anon:<name>] a private anonymous mapping that has been + named by userspace + [anon_shmem:<name>] an anonymous shared memory mapping that has + been named by userspace + =================== =========================================== or if empty, the mapping is anonymous. @@ -442,12 +454,14 @@ Memory Area, or VMA) there is a series of lines such as the following:: MMUPageSize: 4 kB Rss: 892 kB Pss: 374 kB + Pss_Dirty: 0 kB Shared_Clean: 892 kB Shared_Dirty: 0 kB Private_Clean: 0 kB Private_Dirty: 0 kB Referenced: 892 kB Anonymous: 0 kB + KSM: 0 kB LazyFree: 0 kB AnonHugePages: 0 kB ShmemPmdMapped: 0 kB @@ -473,7 +487,9 @@ dirty shared and private pages in the mapping. The "proportional set size" (PSS) of a process is the count of pages it has in memory, where each page is divided by the number of processes sharing it. So if a process has 1000 pages all to itself, and 1000 shared with one other -process, its PSS will be 1500. +process, its PSS will be 1500. "Pss_Dirty" is the portion of PSS which +consists of dirty pages. ("Pss_Clean" is not included, but it can be +calculated by subtracting "Pss_Dirty" from "Pss".) Note that even a page which is part of a MAP_SHARED mapping, but has only a single pte mapped, i.e. is currently used by only one process, is accounted @@ -486,18 +502,21 @@ accessed. a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE and a page is modified, the file page is replaced by a private anonymous copy. +"KSM" reports how many of the pages are KSM pages. Note that KSM-placed zeropages +are not included, only actual KSM pages. + "LazyFree" shows the amount of memory which is marked by madvise(MADV_FREE). The memory isn't freed immediately with madvise(). It's freed in memory pressure if the memory is clean. Please note that the printed value might be lower than the real value due to optimizations used in the current implementation. If this is not desirable please file a bug report. -"AnonHugePages" shows the ammount of memory backed by transparent hugepage. +"AnonHugePages" shows the amount of memory backed by transparent hugepage. -"ShmemPmdMapped" shows the ammount of shared (shmem/tmpfs) memory backed by +"ShmemPmdMapped" shows the amount of shared (shmem/tmpfs) memory backed by huge pages. -"Shared_Hugetlb" and "Private_Hugetlb" show the ammounts of memory backed by +"Shared_Hugetlb" and "Private_Hugetlb" show the amounts of memory backed by hugetlbfs page which is *not* counted in "RSS" or "PSS" field for historical reasons. And these are not included in {Shared,Private}_{Clean,Dirty} field. @@ -508,8 +527,10 @@ replaced by copy-on-write) part of the underlying shmem object out on swap. "SwapPss" shows proportional swap share of this mapping. Unlike "Swap", this does not take into account swapped out page of underlying shmem objects. "Locked" indicates whether the mapping is locked in memory or not. -"THPeligible" indicates whether the mapping is eligible for allocating THP -pages - 1 if true, 0 otherwise. It just shows the current status. + +"THPeligible" indicates whether the mapping is eligible for allocating +naturally aligned THP pages of any currently enabled size. 1 if true, 0 +otherwise. "VmFlags" field deserves a separate description. This member represents the kernel flags associated with the particular virtual memory area in two letter @@ -536,13 +557,20 @@ encoded manner. The codes are the following: ac area is accountable nr swap space is not reserved for the area ht area uses huge tlb pages + sf synchronous page fault ar architecture specific flag + wf wipe on fork dd do not include area into core dump sd soft dirty flag mm mixed map area hg huge page advise flag nh no huge page advise flag - mg mergable advise flag + mg mergeable advise flag + bt arm64 BTI guarded page + mt arm64 MTE allocation tags are enabled + um userfaultfd missing tracking + uw userfaultfd wr-protect tracking + ss shadow stack page == ======================================= Note that there is no guarantee that every flag and associated mnemonic will @@ -661,9 +689,15 @@ files are there, and which are missing. File Content ============ =============================================================== apm Advanced power management info + bootconfig Kernel command line obtained from boot config, + and, if there were kernel parameters from the + boot loader, a "# Parameters from bootloader:" + line followed by a line containing those + parameters prefixed by "# ". (5.5) buddyinfo Kernel memory allocator information (see text) (2.5) bus Directory containing bus specific information - cmdline Kernel command line + cmdline Kernel command line, both from bootloader and embedded + in the kernel image cpuinfo Info about the CPU devices Available devices (block and character) dma Used DMS channels @@ -681,7 +715,14 @@ files are there, and which are missing. kcore Kernel core image (can be ELF or A.OUT(deprecated in 2.4)) kmsg Kernel messages ksyms Kernel symbol table - loadavg Load average of last 1, 5 & 15 minutes + loadavg Load average of last 1, 5 & 15 minutes; + number of processes currently runnable (running or on ready queue); + total number of processes in system; + last pid created. + All fields are separated by one space except "number of + processes currently runnable" and "total number of processes + in system", which are separated by a slash ('/'). Example: + 0.61 0.61 0.55 3/828 22084 locks Kernel locks meminfo Memory info misc Miscellaneous @@ -779,7 +820,7 @@ SPU For this case the APIC will generate the interrupt with a IRQ vector of 0xff. This might also be generated by chipset bugs. -RES, CAL, TLB] +RES, CAL, TLB rescheduling, call and TLB flush interrupts are sent from one CPU to another per the needs of the OS. Typically, their statistics are used by kernel developers and interested users to @@ -791,7 +832,7 @@ suppressed when the system is a uniprocessor. As of this writing, only i386 and x86_64 platforms support the new IRQ vector displays. Of some interest is the introduction of the /proc/irq directory to 2.4. -It could be used to set IRQ to CPU affinity, this means that you can "hook" an +It could be used to set IRQ to CPU affinity. This means that you can "hook" an IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents of the irq subdir is one subdir for each IRQ, and two files; default_smp_affinity and prof_cpu_mask. @@ -805,7 +846,7 @@ For example:: smp_affinity smp_affinity is a bitmask, in which you can specify which CPUs can handle the -IRQ, you can set it by doing:: +IRQ. You can set it by doing:: > echo 1 > /proc/irq/10/smp_affinity @@ -818,7 +859,7 @@ The contents of each smp_affinity file is the same by default:: ffffffff There is an alternate interface, smp_affinity_list which allows specifying -a cpu range instead of a bitmask:: +a CPU range instead of a bitmask:: > cat /proc/irq/0/smp_affinity_list 1024-1031 @@ -832,7 +873,7 @@ reports itself as being attached. This hardware locality information does not include information about any possible driver locality preference. prof_cpu_mask specifies which CPUs are to be profiled by the system wide -profiler. Default value is ffffffff (all cpus if there are only 32 of them). +profiler. Default value is ffffffff (all CPUs if there are only 32 of them). The way IRQs are routed is handled by the IO-APIC, and it's Round Robin between all the CPUs which are allowed to handle it. As usual the kernel has @@ -894,7 +935,7 @@ pagetypeinfo:: Fragmentation avoidance in the kernel works by grouping pages of different migrate types into the same contiguous regions of memory called page blocks. -A page block is typically the size of the default hugepage size e.g. 2MB on +A page block is typically the size of the default hugepage size, e.g. 2MB on X86-64. By keeping pages grouped based on their ability to move, the kernel can reclaim pages within a page block to satisfy a high-order allocation. @@ -916,56 +957,82 @@ meminfo ~~~~~~~ Provides information about distribution and utilization of memory. This -varies by architecture and compile options. The following is from a -16GB PIII, which has highmem enabled. You may not have all of these fields. +varies by architecture and compile options. Some of the counters reported +here overlap. The memory reported by the non overlapping counters may not +add up to the overall memory usage and the difference for some workloads +can be substantial. In many cases there are other means to find out +additional memory using subsystem specific interfaces, for instance +/proc/net/sockstat for TCP memory allocations. + +Example output. You may not have all of these fields. :: > cat /proc/meminfo - MemTotal: 16344972 kB - MemFree: 13634064 kB - MemAvailable: 14836172 kB - Buffers: 3656 kB - Cached: 1195708 kB - SwapCached: 0 kB - Active: 891636 kB - Inactive: 1077224 kB - HighTotal: 15597528 kB - HighFree: 13629632 kB - LowTotal: 747444 kB - LowFree: 4432 kB - SwapTotal: 0 kB - SwapFree: 0 kB - Dirty: 968 kB - Writeback: 0 kB - AnonPages: 861800 kB - Mapped: 280372 kB - Shmem: 644 kB - KReclaimable: 168048 kB - Slab: 284364 kB - SReclaimable: 159856 kB - SUnreclaim: 124508 kB - PageTables: 24448 kB - NFS_Unstable: 0 kB - Bounce: 0 kB - WritebackTmp: 0 kB - CommitLimit: 7669796 kB - Committed_AS: 100056 kB - VmallocTotal: 112216 kB - VmallocUsed: 428 kB - VmallocChunk: 111088 kB - Percpu: 62080 kB - HardwareCorrupted: 0 kB - AnonHugePages: 49152 kB - ShmemHugePages: 0 kB - ShmemPmdMapped: 0 kB + MemTotal: 32858820 kB + MemFree: 21001236 kB + MemAvailable: 27214312 kB + Buffers: 581092 kB + Cached: 5587612 kB + SwapCached: 0 kB + Active: 3237152 kB + Inactive: 7586256 kB + Active(anon): 94064 kB + Inactive(anon): 4570616 kB + Active(file): 3143088 kB + Inactive(file): 3015640 kB + Unevictable: 0 kB + Mlocked: 0 kB + SwapTotal: 0 kB + SwapFree: 0 kB + Zswap: 1904 kB + Zswapped: 7792 kB + Dirty: 12 kB + Writeback: 0 kB + AnonPages: 4654780 kB + Mapped: 266244 kB + Shmem: 9976 kB + KReclaimable: 517708 kB + Slab: 660044 kB + SReclaimable: 517708 kB + SUnreclaim: 142336 kB + KernelStack: 11168 kB + PageTables: 20540 kB + SecPageTables: 0 kB + NFS_Unstable: 0 kB + Bounce: 0 kB + WritebackTmp: 0 kB + CommitLimit: 16429408 kB + Committed_AS: 7715148 kB + VmallocTotal: 34359738367 kB + VmallocUsed: 40444 kB + VmallocChunk: 0 kB + Percpu: 29312 kB + EarlyMemtestBad: 0 kB + HardwareCorrupted: 0 kB + AnonHugePages: 4149248 kB + ShmemHugePages: 0 kB + ShmemPmdMapped: 0 kB + FileHugePages: 0 kB + FilePmdMapped: 0 kB + CmaTotal: 0 kB + CmaFree: 0 kB + HugePages_Total: 0 + HugePages_Free: 0 + HugePages_Rsvd: 0 + HugePages_Surp: 0 + Hugepagesize: 2048 kB + Hugetlb: 0 kB + DirectMap4k: 401152 kB + DirectMap2M: 10008576 kB + DirectMap1G: 24117248 kB MemTotal - Total usable ram (i.e. physical ram minus a few reserved + Total usable RAM (i.e. physical RAM minus a few reserved bits and the kernel binary code) MemFree - The sum of LowFree+HighFree + Total free RAM. On highmem systems, the sum of LowFree+HighFree MemAvailable An estimate of how much memory is available for starting new applications, without swapping. Calculated from MemFree, @@ -979,8 +1046,9 @@ Buffers Relatively temporary storage for raw disk blocks shouldn't get tremendously large (20MB or so) Cached - in-memory cache for files read from the disk (the - pagecache). Doesn't include SwapCached + In-memory cache for files read from the disk (the + pagecache) as well as tmpfs & shmem. + Doesn't include SwapCached. SwapCached Memory that once was swapped out, is swapped back in but still also is in the swapfile (if memory is needed it @@ -992,8 +1060,13 @@ Active Inactive Memory which has been less recently used. It is more eligible to be reclaimed for other purposes +Unevictable + Memory allocated for userspace which cannot be reclaimed, such + as mlocked pages, ramfs backing pages, secret memfd pages etc. +Mlocked + Memory locked with mlock(). HighTotal, HighFree - Highmem is all memory above ~860MB of physical memory + Highmem is all memory above ~860MB of physical memory. Highmem areas are for use by userspace programs, or for the pagecache. The kernel must use tricks to access this memory, making it slower to access than lowmem. @@ -1008,26 +1081,20 @@ SwapTotal SwapFree Memory which has been evicted from RAM, and is temporarily on the disk +Zswap + Memory consumed by the zswap backend (compressed size) +Zswapped + Amount of anonymous memory stored in zswap (original size) Dirty Memory which is waiting to get written back to the disk Writeback Memory which is actively being written back to the disk AnonPages Non-file backed pages mapped into userspace page tables -HardwareCorrupted - The amount of RAM/memory in KB, the kernel identifies as - corrupted. -AnonHugePages - Non-file backed huge pages mapped into userspace page tables Mapped - files which have been mmaped, such as libraries + files which have been mmapped, such as libraries Shmem Total memory used by shared memory (shmem) and tmpfs -ShmemHugePages - Memory used by shared memory (shmem) and tmpfs allocated - with huge pages -ShmemPmdMapped - Shared memory mapped into userspace with huge pages KReclaimable Kernel allocations that the kernel will attempt to reclaim under memory pressure. Includes SReclaimable (below), and other @@ -1038,12 +1105,16 @@ SReclaimable Part of Slab, that might be reclaimed, such as caches SUnreclaim Part of Slab, that cannot be reclaimed on memory pressure +KernelStack + Memory consumed by the kernel stacks of all tasks PageTables - amount of memory dedicated to the lowest level of page - tables. + Memory consumed by userspace page tables +SecPageTables + Memory consumed by secondary page tables, this currently + currently includes KVM mmu allocations on x86 and arm64. NFS_Unstable - NFS pages sent to the server, but not yet committed to stable - storage + Always zero. Previous counted pages which had been written to + the server, but has not been committed to stable storage. Bounce Memory used for block device "bounce buffers" WritebackTmp @@ -1065,23 +1136,23 @@ CommitLimit yield a CommitLimit of 7.3G. For more details, see the memory overcommit documentation - in vm/overcommit-accounting. + in mm/overcommit-accounting. Committed_AS The amount of memory presently allocated on the system. The committed memory is a sum of all of the memory which has been allocated by processes, even if it has not been "used" by them as of yet. A process which malloc()'s 1G of memory, but only touches 300M of it will show up as - using 1G. This 1G is memory which has been "committed" to + using 1G. This 1G is memory which has been "committed" to by the VM and can be used at any time by the allocating application. With strict overcommit enabled on the system - (mode 2 in 'vm.overcommit_memory'),allocations which would + (mode 2 in 'vm.overcommit_memory'), allocations which would exceed the CommitLimit (detailed above) will not be permitted. This is useful if one needs to guarantee that processes will not fail due to lack of memory once that memory has been successfully allocated. VmallocTotal - total size of vmalloc memory area + total size of vmalloc virtual address space VmallocUsed amount of vmalloc area which is used VmallocChunk @@ -1089,6 +1160,37 @@ VmallocChunk Percpu Memory allocated to the percpu allocator used to back percpu allocations. This stat excludes the cost of metadata. +EarlyMemtestBad + The amount of RAM/memory in kB, that was identified as corrupted + by early memtest. If memtest was not run, this field will not + be displayed at all. Size is never rounded down to 0 kB. + That means if 0 kB is reported, you can safely assume + there was at least one pass of memtest and none of the passes + found a single faulty byte of RAM. +HardwareCorrupted + The amount of RAM/memory in KB, the kernel identifies as + corrupted. +AnonHugePages + Non-file backed huge pages mapped into userspace page tables +ShmemHugePages + Memory used by shared memory (shmem) and tmpfs allocated + with huge pages +ShmemPmdMapped + Shared memory mapped into userspace with huge pages +FileHugePages + Memory used for filesystem data (page cache) allocated + with huge pages +FilePmdMapped + Page cache mapped into userspace with huge pages +CmaTotal + Memory reserved for the Contiguous Memory Allocator (CMA) +CmaFree + Free remaining memory in the CMA reserves +HugePages_Total, HugePages_Free, HugePages_Rsvd, HugePages_Surp, Hugepagesize, Hugetlb + See Documentation/admin-guide/mm/hugetlbpage.rst. +DirectMap4k, DirectMap2M, DirectMap1G + Breakdown of page table sizes used in the kernel's + identity mapping of RAM vmallocinfo ~~~~~~~~~~~ @@ -1096,7 +1198,7 @@ vmallocinfo Provides information about vmalloced/vmaped areas. One line per area, containing the virtual address range of the area, size in bytes, caller information of the creator, and optional information depending -on the kind of area : +on the kind of area: ========== =================================================== pages=nr number of pages @@ -1141,101 +1243,23 @@ on the kind of area : softirqs ~~~~~~~~ -Provides counts of softirq handlers serviced since boot time, for each cpu. +Provides counts of softirq handlers serviced since boot time, for each CPU. :: > cat /proc/softirqs - CPU0 CPU1 CPU2 CPU3 + CPU0 CPU1 CPU2 CPU3 HI: 0 0 0 0 - TIMER: 27166 27120 27097 27034 + TIMER: 27166 27120 27097 27034 NET_TX: 0 0 0 17 NET_RX: 42 0 0 39 - BLOCK: 0 0 107 1121 - TASKLET: 0 0 0 290 - SCHED: 27035 26983 26971 26746 - HRTIMER: 0 0 0 0 - RCU: 1678 1769 2178 2250 - - -1.3 IDE devices in /proc/ide ----------------------------- - -The subdirectory /proc/ide contains information about all IDE devices of which -the kernel is aware. There is one subdirectory for each IDE controller, the -file drivers and a link for each IDE device, pointing to the device directory -in the controller specific subtree. - -The file drivers contains general information about the drivers used for the -IDE devices:: - - > cat /proc/ide/drivers - ide-cdrom version 4.53 - ide-disk version 1.08 - -More detailed information can be found in the controller specific -subdirectories. These are named ide0, ide1 and so on. Each of these -directories contains the files shown in table 1-6. - - -.. table:: Table 1-6: IDE controller info in /proc/ide/ide? - - ======= ======================================= - File Content - ======= ======================================= - channel IDE channel (0 or 1) - config Configuration (only for PCI/IDE bridge) - mate Mate name - model Type/Chipset of IDE controller - ======= ======================================= - -Each device connected to a controller has a separate subdirectory in the -controllers directory. The files listed in table 1-7 are contained in these -directories. - - -.. table:: Table 1-7: IDE device information - - ================ ========================================== - File Content - ================ ========================================== - cache The cache - capacity Capacity of the medium (in 512Byte blocks) - driver driver and version - geometry physical and logical geometry - identify device identify block - media media type - model device identifier - settings device setup - smart_thresholds IDE disk management thresholds - smart_values IDE disk management values - ================ ========================================== - -The most interesting file is ``settings``. This file contains a nice -overview of the drive parameters:: - - # cat /proc/ide/ide0/hda/settings - name value min max mode - ---- ----- --- --- ---- - bios_cyl 526 0 65535 rw - bios_head 255 0 255 rw - bios_sect 63 0 63 rw - breada_readahead 4 0 127 rw - bswap 0 0 1 r - file_readahead 72 0 2097151 rw - io_32bit 0 0 3 rw - keepsettings 0 0 1 rw - max_kb_per_request 122 1 127 rw - multcount 0 0 8 rw - nice1 1 0 1 rw - nowerr 0 0 1 rw - pio_mode write-only 0 255 w - slow 0 0 1 rw - unmaskirq 0 0 1 rw - using_dma 0 0 1 rw - - -1.4 Networking info in /proc/net + BLOCK: 0 0 107 1121 + TASKLET: 0 0 0 290 + SCHED: 27035 26983 26971 26746 + HRTIMER: 0 0 0 0 + RCU: 1678 1769 2178 2250 + +1.3 Networking info in /proc/net -------------------------------- The subdirectory /proc/net follows the usual pattern. Table 1-8 shows the @@ -1281,6 +1305,7 @@ support this. Table 1-9 lists the files and their meaning. rt_cache Routing cache snmp SNMP data sockstat Socket statistics + softnet_stat Per-CPU incoming packets queues statistics of online CPUs tcp TCP sockets udp UDP sockets unix UNIX domain sockets @@ -1314,12 +1339,12 @@ It will contain information that is specific to that bond, such as the current slaves of the bond, the link status of the slaves, and how many times the slaves link has failed. -1.5 SCSI info +1.4 SCSI info ------------- -If you have a SCSI host adapter in your system, you'll find a subdirectory -named after the driver for this adapter in /proc/scsi. You'll also see a list -of all recognized SCSI devices in /proc/scsi:: +If you have a SCSI or ATA host adapter in your system, you'll find a +subdirectory named after the driver for this adapter in /proc/scsi. +You'll also see a list of all recognized SCSI devices in /proc/scsi:: >cat /proc/scsi/scsi Attached devices: @@ -1377,7 +1402,7 @@ AHA-2940 SCSI adapter:: Total transfers 0 (0 reads and 0 writes) -1.6 Parallel port info in /proc/parport +1.5 Parallel port info in /proc/parport --------------------------------------- The directory /proc/parport contains information about the parallel ports of @@ -1402,11 +1427,11 @@ These directories contain the four files shown in Table 1-10. number or none). ========= ==================================================================== -1.7 TTY info in /proc/tty +1.6 TTY info in /proc/tty ------------------------- Information about the available and actually used tty's can be found in the -directory /proc/tty.You'll find entries for drivers and line disciplines in +directory /proc/tty. You'll find entries for drivers and line disciplines in this directory, as shown in Table 1-11. @@ -1437,7 +1462,7 @@ To see which tty's are currently in use, you can simply look into the file unknown /dev/tty 4 1-63 console -1.8 Miscellaneous kernel statistics in /proc/stat +1.7 Miscellaneous kernel statistics in /proc/stat ------------------------------------------------- Various pieces of information about kernel activity are available in the @@ -1445,16 +1470,18 @@ Various pieces of information about kernel activity are available in the since the system first booted. For a quick look, simply cat the file:: > cat /proc/stat - cpu 2255 34 2290 22625563 6290 127 456 0 0 0 - cpu0 1132 34 1441 11311718 3675 127 438 0 0 0 - cpu1 1123 0 849 11313845 2614 0 18 0 0 0 - intr 114930548 113199788 3 0 5 263 0 4 [... lots more numbers ...] - ctxt 1990473 - btime 1062191376 - processes 2915 - procs_running 1 + cpu 237902850 368826709 106375398 1873517540 1135548 0 14507935 0 0 0 + cpu0 60045249 91891769 26331539 468411416 495718 0 5739640 0 0 0 + cpu1 59746288 91759249 26609887 468860630 312281 0 4384817 0 0 0 + cpu2 59489247 92985423 26904446 467808813 171668 0 2268998 0 0 0 + cpu3 58622065 92190267 26529524 468436680 155879 0 2114478 0 0 0 + intr 8688370575 8 3373 0 0 0 0 0 0 1 40791 0 0 353317 0 0 0 0 224789828 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 190974333 41958554 123983334 43 0 224593 0 0 0 <more 0's deleted> + ctxt 22848221062 + btime 1605316999 + processes 746787147 + procs_running 2 procs_blocked 0 - softirq 183433 0 21755 12 39 1137 231 21459 2263 + softirq 12121874454 100099120 3938138295 127375644 2795979 187870761 0 173808342 3072582055 52608 224184354 The very first "cpu" line aggregates the numbers in all of the other "cpuN" lines. These numbers identify the amount of time the CPU has spent performing @@ -1468,9 +1495,9 @@ second). The meanings of the columns are as follows, from left to right: - iowait: In a word, iowait stands for waiting for I/O to complete. But there are several problems: - 1. Cpu will not wait for I/O to complete, iowait is the time that a task is - waiting for I/O to complete. When cpu goes into idle state for - outstanding task io, another task will be scheduled on this CPU. + 1. CPU will not wait for I/O to complete, iowait is the time that a task is + waiting for I/O to complete. When CPU goes into idle state for + outstanding task I/O, another task will be scheduled on this CPU. 2. In a multi-core CPU, the task waiting for I/O to complete is not running on any CPU, so the iowait of each CPU is difficult to calculate. 3. The value of iowait field in /proc/stat will decrease in certain @@ -1510,14 +1537,14 @@ softirqs serviced; each subsequent column is the total for that particular softirq. -1.9 Ext4 file system parameters +1.8 Ext4 file system parameters ------------------------------- Information about mounted ext4 file systems can be found in /proc/fs/ext4. Each mounted filesystem will have a directory in /proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or -/proc/fs/ext4/dm-0). The files in each per-device directory are shown -in Table 1-12, below. +/proc/fs/ext4/sda9 or /proc/fs/ext4/dm-0). The files in each per-device +directory are shown in Table 1-12, below. .. table:: Table 1-12: Files in /proc/fs/ext4/<devname> @@ -1526,8 +1553,8 @@ in Table 1-12, below. mb_groups details of multiblock allocator buddy cache of free blocks ============== ========================================================== -2.0 /proc/consoles ------------------- +1.9 /proc/consoles +------------------- Shows registered system console lines. To see which character device lines are currently used for the system console @@ -1587,10 +1614,9 @@ production system. Set up a development machine and test to make sure that everything works the way you want it to. You may have no alternative but to reboot the machine once an error has been made. -To change a value, simply echo the new value into the file. An example is -given below in the section on the file system data. You need to be root to do -this. You can create your own boot script to perform this every time your -system boots. +To change a value, simply echo the new value into the file. +You need to be root to do this. You can create your own boot script +to perform this every time your system boots. The files in /proc/sys can be used to fine tune and monitor miscellaneous and general things in the operation of the Linux kernel. Since some of the files @@ -1598,12 +1624,12 @@ can inadvertently disrupt your system, it is advisable to read both documentation and source before actually making adjustments. In any case, be very careful when writing to any of these files. The entries in /proc may change slightly between the 2.1.* and the 2.2 kernel, so if there is any doubt -review the kernel documentation in the directory /usr/src/linux/Documentation. +review the kernel documentation in the directory linux/Documentation. This chapter is heavily based on the documentation included in the pre 2.2 kernels, and became part of it in version 2.2.1 of the Linux kernel. -Please see: Documentation/admin-guide/sysctl/ directory for descriptions of these -entries. +Please see: Documentation/admin-guide/sysctl/ directory for descriptions of +these entries. Summary ------- @@ -1621,8 +1647,8 @@ Chapter 3: Per-process Parameters 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj- Adjust the oom-killer score -------------------------------------------------------------------------------- -These file can be used to adjust the badness heuristic used to select which -process gets killed in out of memory conditions. +These files can be used to adjust the badness heuristic used to select which +process gets killed in out of memory (oom) conditions. The badness heuristic assigns a value to each candidate task ranging from 0 (never kill) to 1000 (always kill) to determine which process is targeted. The @@ -1631,9 +1657,6 @@ may allocate from based on an estimation of its current memory and swap use. For example, if a task is using all allowed memory, its badness score will be 1000. If it is using half of its allowed memory, its score will be 500. -There is an additional factor included in the badness score: the current memory -and swap usage is discounted by 3% for root processes. - The amount of "allowed" memory depends on the context in which the oom killer was called. If it is due to the memory assigned to the allocating task's cpuset being exhausted, the allowed memory represents the set of mems assigned to that @@ -1669,24 +1692,22 @@ The value of /proc/<pid>/oom_score_adj may be reduced no lower than the last value set by a CAP_SYS_RESOURCE process. To reduce the value any lower requires CAP_SYS_RESOURCE. -Caveat: when a parent task is selected, the oom killer will sacrifice any first -generation children with separate address spaces instead, if possible. This -avoids servers and important system daemons from being killed and loses the -minimal amount of work. - 3.2 /proc/<pid>/oom_score - Display current oom-killer score ------------------------------------------------------------- -This file can be used to check the current score used by the oom-killer is for +This file can be used to check the current score used by the oom-killer for any given <pid>. Use it together with /proc/<pid>/oom_score_adj to tune which process should be killed in an out-of-memory situation. +Please note that the exported value includes oom_score_adj so it is +effectively in range [0,2000]. + 3.3 /proc/<pid>/io - Display the IO accounting fields ------------------------------------------------------- -This file contains IO statistics for each running process +This file contains IO statistics for each running process. Example ~~~~~~~ @@ -1717,7 +1738,7 @@ The number of bytes which this task has caused to be read from storage. This is simply the sum of bytes which this process passed to read() and pread(). It includes things like tty IO and it is unaffected by whether or not actual physical disk IO was required (the read might have been satisfied from -pagecache) +pagecache). wchar @@ -1839,19 +1860,19 @@ For example:: This file contains lines of the form:: 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue - (1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11) - - (1) mount ID: unique identifier of the mount (may be reused after umount) - (2) parent ID: ID of parent (or of self for the top of the mount tree) - (3) major:minor: value of st_dev for files on filesystem - (4) root: root of the mount within the filesystem - (5) mount point: mount point relative to the process's root - (6) mount options: per mount options - (7) optional fields: zero or more fields of the form "tag[:value]" - (8) separator: marks the end of the optional fields - (9) filesystem type: name of filesystem of the form "type[.subtype]" - (10) mount source: filesystem specific information or "none" - (11) super options: per super block options + (1)(2)(3) (4) (5) (6) (n…m) (m+1)(m+2) (m+3) (m+4) + + (1) mount ID: unique identifier of the mount (may be reused after umount) + (2) parent ID: ID of parent (or of self for the top of the mount tree) + (3) major:minor: value of st_dev for files on filesystem + (4) root: root of the mount within the filesystem + (5) mount point: mount point relative to the process's root + (6) mount options: per mount options + (n…m) optional fields: zero or more fields of the form "tag[:value]" + (m+1) separator: marks the end of the optional fields + (m+2) filesystem type: name of filesystem of the form "type[.subtype]" + (m+3) mount source: filesystem specific information or "none" + (m+4) super options: per super block options Parsers should ignore all unrecognised optional fields. Currently the possible optional fields are: @@ -1870,12 +1891,12 @@ unbindable mount is unbindable For more information on mount propagation see: - Documentation/filesystems/sharedsubtree.txt + Documentation/filesystems/sharedsubtree.rst 3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm -------------------------------------------------------- -These files provide a method to access a tasks comm value. It also allows for +These files provide a method to access a task's comm value. It also allows for a task to set its own or one of its thread siblings comm value. The comm value is limited in size compared to the cmdline value, so writing anything longer then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated @@ -1888,32 +1909,34 @@ This file provides a fast way to retrieve first level children pids of a task pointed by <pid>/<tid> pair. The format is a space separated stream of pids. -Note the "first level" here -- if a child has own children they will -not be listed here, one needs to read /proc/<children-pid>/task/<tid>/children +Note the "first level" here -- if a child has its own children they will +not be listed here; one needs to read /proc/<children-pid>/task/<tid>/children to obtain the descendants. Since this interface is intended to be fast and cheap it doesn't guarantee to provide precise results and some children might be skipped, especially if they've exited right after we printed their -pids, so one need to either stop or freeze processes being inspected +pids, so one needs to either stop or freeze processes being inspected if precise results are needed. 3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file --------------------------------------------------------------- This file provides information associated with an opened file. The regular -files have at least three fields -- 'pos', 'flags' and mnt_id. The 'pos' -represents the current offset of the opened file in decimal form [see lseek(2) -for details], 'flags' denotes the octal O_xxx mask the file has been -created with [see open(2) for details] and 'mnt_id' represents mount ID of -the file system containing the opened file [see 3.5 /proc/<pid>/mountinfo -for details]. +files have at least four fields -- 'pos', 'flags', 'mnt_id' and 'ino'. +The 'pos' represents the current offset of the opened file in decimal +form [see lseek(2) for details], 'flags' denotes the octal O_xxx mask the +file has been created with [see open(2) for details] and 'mnt_id' represents +mount ID of the file system containing the opened file [see 3.5 +/proc/<pid>/mountinfo for details]. 'ino' represents the inode number of +the file. A typical output is:: pos: 0 flags: 0100002 mnt_id: 19 + ino: 63107 All locks associated with a file descriptor are shown in its fdinfo too:: @@ -1930,6 +1953,7 @@ Eventfd files pos: 0 flags: 04002 mnt_id: 9 + ino: 63107 eventfd-count: 5a where 'eventfd-count' is hex value of a counter. @@ -1942,6 +1966,7 @@ Signalfd files pos: 0 flags: 04002 mnt_id: 9 + ino: 63107 sigmask: 0000000000000200 where 'sigmask' is hex value of the signal mask associated @@ -1955,6 +1980,7 @@ Epoll files pos: 0 flags: 02 mnt_id: 9 + ino: 63107 tfd: 5 events: 1d data: ffffffffffffffff pos:0 ino:61af sdev:7 where 'tfd' is a target file descriptor number in decimal form, @@ -1971,9 +1997,11 @@ For inotify files the format is the following:: pos: 0 flags: 02000000 + mnt_id: 9 + ino: 63107 inotify wd:3 ino:9e7e sdev:800013 mask:800afce ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_handle:7e9e0000640d1b6d -where 'wd' is a watch descriptor in decimal form, ie a target file +where 'wd' is a watch descriptor in decimal form, i.e. a target file descriptor number, 'ino' and 'sdev' are inode and device where the target file resides and the 'mask' is the mask of events, all in hex form [see inotify(7) for more details]. @@ -1993,6 +2021,7 @@ For fanotify files the format is:: pos: 0 flags: 02 mnt_id: 9 + ino: 63107 fanotify flags:10 event-flags:0 fanotify mnt_id:12 mflags:40 mask:38 ignored_mask:40000003 fanotify ino:4f969 sdev:800013 mflags:0 mask:3b ignored_mask:40000000 fhandle-bytes:8 fhandle-type:1 f_handle:69f90400c275b5b4 @@ -2000,10 +2029,10 @@ For fanotify files the format is:: where fanotify 'flags' and 'event-flags' are values used in fanotify_init call, 'mnt_id' is the mount point identifier, 'mflags' is the value of flags associated with mark which are tracked separately from events -mask. 'ino', 'sdev' are target inode and device, 'mask' is the events +mask. 'ino' and 'sdev' are target inode and device, 'mask' is the events mask and 'ignored_mask' is the mask of events which are to be ignored. -All in hex format. Incorporation of 'mflags', 'mask' and 'ignored_mask' -does provide information about flags and mask used in fanotify_mark +All are in hex format. Incorporation of 'mflags', 'mask' and 'ignored_mask' +provide information about flags and mask used in fanotify_mark call [see fsnotify manpage for details]. While the first three lines are mandatory and always printed, the rest is @@ -2017,6 +2046,7 @@ Timerfd files pos: 0 flags: 02 mnt_id: 9 + ino: 63107 clockid: 0 ticks: 0 settime flags: 01 @@ -2026,11 +2056,27 @@ Timerfd files where 'clockid' is the clock type and 'ticks' is the number of the timer expirations that have occurred [see timerfd_create(2) for details]. 'settime flags' are flags in octal form been used to setup the timer [see timerfd_settime(2) for -details]. 'it_value' is remaining time until the timer exiration. +details]. 'it_value' is remaining time until the timer expiration. 'it_interval' is the interval for the timer. Note the timer might be set up with TIMER_ABSTIME option which will be shown in 'settime flags', but 'it_value' still exhibits timer's remaining time. +DMA Buffer files +~~~~~~~~~~~~~~~~ + +:: + + pos: 0 + flags: 04002 + mnt_id: 9 + ino: 63107 + size: 32768 + count: 2 + exp_name: system-heap + +where 'size' is the size of the DMA buffer in bytes. 'count' is the file count of +the DMA buffer file. 'exp_name' is the name of the DMA buffer exporter. + 3.9 /proc/<pid>/map_files - Information about memory mapped files --------------------------------------------------------------------- This directory contains symbolic links which represent memory mapped files @@ -2056,13 +2102,13 @@ are actually shared. 3.10 /proc/<pid>/timerslack_ns - Task timerslack value --------------------------------------------------------- This file provides the value of the task's timerslack value in nanoseconds. -This value specifies a amount of time that normal timers may be deferred +This value specifies an amount of time that normal timers may be deferred in order to coalesce timers and avoid unnecessary wakeups. -This allows a task's interactivity vs power consumption trade off to be +This allows a task's interactivity vs power consumption tradeoff to be adjusted. -Writing 0 to the file will set the tasks timerslack to the default value. +Writing 0 to the file will set the task's timerslack to the default value. Valid values are from 0 - ULLONG_MAX @@ -2102,10 +2148,10 @@ Example Description ~~~~~~~~~~~ -x86 specific entries: +x86 specific entries ~~~~~~~~~~~~~~~~~~~~~ -AVX512_elapsed_ms: +AVX512_elapsed_ms ^^^^^^^^^^^^^^^^^^ If AVX512 is supported on the machine, this entry shows the milliseconds @@ -2131,8 +2177,24 @@ AVX512_elapsed_ms: the task is unlikely an AVX512 user, but depends on the workload and the scheduling scenario, it also could be a false negative mentioned above. -Configuring procfs ------------------- +3.13 /proc/<pid>/fd - List of symlinks to open files +------------------------------------------------------- +This directory contains symbolic links which represent open files +the process is maintaining. Example output:: + + lr-x------ 1 root root 64 Sep 20 17:53 0 -> /dev/null + l-wx------ 1 root root 64 Sep 20 17:53 1 -> /dev/null + lrwx------ 1 root root 64 Sep 20 17:53 10 -> 'socket:[12539]' + lrwx------ 1 root root 64 Sep 20 17:53 11 -> 'socket:[12540]' + lrwx------ 1 root root 64 Sep 20 17:53 12 -> 'socket:[12542]' + +The number of open files for the process is stored in 'size' member +of stat() output for /proc/<pid>/fd for fast access. +------------------------------------------------------- + + +Chapter 4: Configuring procfs +============================= 4.1 Mount options --------------------- @@ -2142,28 +2204,78 @@ The following mount options are supported: ========= ======================================================== hidepid= Set /proc/<pid>/ access mode. gid= Set the group authorized to learn processes information. + subset= Show only the specified subset of procfs. ========= ======================================================== -hidepid=0 means classic mode - everybody may access all /proc/<pid>/ directories -(default). - -hidepid=1 means users may not access any /proc/<pid>/ directories but their -own. Sensitive files like cmdline, sched*, status are now protected against -other users. This makes it impossible to learn whether any user runs -specific program (given the program doesn't reveal itself by its behaviour). -As an additional bonus, as /proc/<pid>/cmdline is unaccessible for other users, -poorly written programs passing sensitive information via program arguments are -now protected against local eavesdroppers. - -hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be fully invisible to other -users. It doesn't mean that it hides a fact whether a process with a specific -pid value exists (it can be learned by other means, e.g. by "kill -0 $PID"), -but it hides process' uid and gid, which may be learned by stat()'ing -/proc/<pid>/ otherwise. It greatly complicates an intruder's task of gathering -information about running processes, whether some daemon runs with elevated -privileges, whether other user runs some sensitive program, whether other users -run any program at all, etc. +hidepid=off or hidepid=0 means classic mode - everybody may access all +/proc/<pid>/ directories (default). + +hidepid=noaccess or hidepid=1 means users may not access any /proc/<pid>/ +directories but their own. Sensitive files like cmdline, sched*, status are now +protected against other users. This makes it impossible to learn whether any +user runs specific program (given the program doesn't reveal itself by its +behaviour). As an additional bonus, as /proc/<pid>/cmdline is unaccessible for +other users, poorly written programs passing sensitive information via program +arguments are now protected against local eavesdroppers. + +hidepid=invisible or hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be +fully invisible to other users. It doesn't mean that it hides a fact whether a +process with a specific pid value exists (it can be learned by other means, e.g. +by "kill -0 $PID"), but it hides process' uid and gid, which may be learned by +stat()'ing /proc/<pid>/ otherwise. It greatly complicates an intruder's task of +gathering information about running processes, whether some daemon runs with +elevated privileges, whether other user runs some sensitive program, whether +other users run any program at all, etc. + +hidepid=ptraceable or hidepid=4 means that procfs should only contain +/proc/<pid>/ directories that the caller can ptrace. gid= defines a group authorized to learn processes information otherwise prohibited by hidepid=. If you use some daemon like identd which needs to learn information about processes information, just add identd to this group. + +subset=pid hides all top level files and directories in the procfs that +are not related to tasks. + +Chapter 5: Filesystem behavior +============================== + +Originally, before the advent of pid namespace, procfs was a global file +system. It means that there was only one procfs instance in the system. + +When pid namespace was added, a separate procfs instance was mounted in +each pid namespace. So, procfs mount options are global among all +mountpoints within the same namespace:: + + # grep ^proc /proc/mounts + proc /proc proc rw,relatime,hidepid=2 0 0 + + # strace -e mount mount -o hidepid=1 -t proc proc /tmp/proc + mount("proc", "/tmp/proc", "proc", 0, "hidepid=1") = 0 + +++ exited with 0 +++ + + # grep ^proc /proc/mounts + proc /proc proc rw,relatime,hidepid=2 0 0 + proc /tmp/proc proc rw,relatime,hidepid=2 0 0 + +and only after remounting procfs mount options will change at all +mountpoints:: + + # mount -o remount,hidepid=1 -t proc proc /tmp/proc + + # grep ^proc /proc/mounts + proc /proc proc rw,relatime,hidepid=1 0 0 + proc /tmp/proc proc rw,relatime,hidepid=1 0 0 + +This behavior is different from the behavior of other filesystems. + +The new procfs behavior is more like other filesystems. Each procfs mount +creates a new procfs instance. Mount options affect own procfs instance. +It means that it became possible to have several procfs instances +displaying tasks with different filtering options in one pid namespace:: + + # mount -o hidepid=invisible -t proc proc /proc + # mount -o hidepid=noaccess -t proc proc /tmp/proc + # grep ^proc /proc/mounts + proc /proc proc rw,relatime,hidepid=invisible 0 0 + proc /tmp/proc proc rw,relatime,hidepid=noaccess 0 0 |