diff options
Diffstat (limited to 'Documentation/vm/free_page_reporting.rst')
| -rw-r--r-- | Documentation/vm/free_page_reporting.rst | 40 |
1 files changed, 0 insertions, 40 deletions
diff --git a/Documentation/vm/free_page_reporting.rst b/Documentation/vm/free_page_reporting.rst deleted file mode 100644 index 8c05e62d8b2b..000000000000 --- a/Documentation/vm/free_page_reporting.rst +++ /dev/null @@ -1,40 +0,0 @@ -.. _free_page_reporting: - -===================== -Free Page Reporting -===================== - -Free page reporting is an API by which a device can register to receive -lists of pages that are currently unused by the system. This is useful in -the case of virtualization where a guest is then able to use this data to -notify the hypervisor that it is no longer using certain pages in memory. - -For the driver, typically a balloon driver, to use of this functionality -it will allocate and initialize a page_reporting_dev_info structure. The -field within the structure it will populate is the "report" function -pointer used to process the scatterlist. It must also guarantee that it can -handle at least PAGE_REPORTING_CAPACITY worth of scatterlist entries per -call to the function. A call to page_reporting_register will register the -page reporting interface with the reporting framework assuming no other -page reporting devices are already registered. - -Once registered the page reporting API will begin reporting batches of -pages to the driver. The API will start reporting pages 2 seconds after -the interface is registered and will continue to do so 2 seconds after any -page of a sufficiently high order is freed. - -Pages reported will be stored in the scatterlist passed to the reporting -function with the final entry having the end bit set in entry nent - 1. -While pages are being processed by the report function they will not be -accessible to the allocator. Once the report function has been completed -the pages will be returned to the free area from which they were obtained. - -Prior to removing a driver that is making use of free page reporting it -is necessary to call page_reporting_unregister to have the -page_reporting_dev_info structure that is currently in use by free page -reporting removed. Doing this will prevent further reports from being -issued via the interface. If another driver or the same driver is -registered it is possible for it to resume where the previous driver had -left off in terms of reporting free pages. - -Alexander Duyck, Dec 04, 2019 |