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From f4a6415f8d5fa447868d1fdc7119e0a328966379 Mon Sep 17 00:00:00 2001
From: Kienan Stewart <kstewart@efficios.com>
Date: Mon, 25 Mar 2024 10:30:32 -0400
Subject: [PATCH 3/4] Fix: mm_compaction_migratepages changed in linux 6.9-rc1
See upstream commit:
commit ab755bf4249b992fc2140d615ab0a686d50765b4
Author: Baolin Wang <baolin.wang@linux.alibaba.com>
Date: Tue Feb 20 14:16:31 2024 +0800
mm: compaction: update the cc->nr_migratepages when allocating or freeing the freepages
Currently we will use 'cc->nr_freepages >= cc->nr_migratepages' comparison
to ensure that enough freepages are isolated in isolate_freepages(),
however it just decreases the cc->nr_freepages without updating
cc->nr_migratepages in compaction_alloc(), which will waste more CPU
cycles and cause too many freepages to be isolated.
So we should also update the cc->nr_migratepages when allocating or
freeing the freepages to avoid isolating excess freepages. And I can see
fewer free pages are scanned and isolated when running thpcompact on my
Arm64 server:
k6.7 k6.7_patched
Ops Compaction pages isolated 120692036.00 118160797.00
Ops Compaction migrate scanned 131210329.00 154093268.00
Ops Compaction free scanned 1090587971.00 1080632536.00
Ops Compact scan efficiency 12.03 14.26
Moreover, I did not see an obvious latency improvements, this is likely
because isolating freepages is not the bottleneck in the thpcompact test
case.
k6.7 k6.7_patched
Amean fault-both-1 1089.76 ( 0.00%) 1080.16 * 0.88%*
Amean fault-both-3 1616.48 ( 0.00%) 1636.65 * -1.25%*
Amean fault-both-5 2266.66 ( 0.00%) 2219.20 * 2.09%*
Amean fault-both-7 2909.84 ( 0.00%) 2801.90 * 3.71%*
Amean fault-both-12 4861.26 ( 0.00%) 4733.25 * 2.63%*
Amean fault-both-18 7351.11 ( 0.00%) 6950.51 * 5.45%*
Amean fault-both-24 9059.30 ( 0.00%) 9159.99 * -1.11%*
Amean fault-both-30 10685.68 ( 0.00%) 11399.02 * -6.68%*
Upstream-Status: Backport [175fe77c Fix: mm_compaction_migratepages changed in linux 6.9-rc1]
Change-Id: I103a43fd1b549360b3fc978fd409b7c17ef3e192
Signed-off-by: Kienan Stewart <kstewart@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---
include/instrumentation/events/compaction.h | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)
Index: lttng-modules-2.13.12/include/instrumentation/events/compaction.h
===================================================================
--- lttng-modules-2.13.12.orig/include/instrumentation/events/compaction.h
+++ lttng-modules-2.13.12/include/instrumentation/events/compaction.h
@@ -97,7 +97,22 @@ LTTNG_TRACEPOINT_EVENT_INSTANCE_MAP(comp
#endif /* #else #if LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,0,0) */
-#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,18,0) || \
+#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(6,9,0))
+LTTNG_TRACEPOINT_EVENT_MAP(mm_compaction_migratepages,
+
+ compaction_migratepages,
+
+ TP_PROTO(unsigned int nr_migratepages,
+ unsigned int nr_succeeded),
+
+ TP_ARGS(nr_migratepages, nr_succeeded),
+
+ TP_FIELDS(
+ ctf_integer(unsigned long, nr_migrated, nr_succeeded)
+ ctf_integer(unsigned long, nr_failed, nr_migratepages - nr_succeeded)
+ )
+)
+#elif (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,18,0) || \
LTTNG_RHEL_KERNEL_RANGE(5,14,0,163,0,0, 5,15,0,0,0,0))
LTTNG_TRACEPOINT_EVENT_MAP(mm_compaction_migratepages,
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