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| author | Anshuman Khandual <anshuman.khandual@arm.com> | 2020-08-12 03:31:51 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-08-12 19:57:57 +0200 |
| commit | 1a5bae25e3cf95c4e83a97f87a6b5280d9acbb22 (patch) | |
| tree | dc992bcf615ef29415565caa5d6938e9870d75bc /Documentation/vm | |
| parent | mm: thp: remove debug_cow switch (diff) | |
| download | linux-1a5bae25e3cf95c4e83a97f87a6b5280d9acbb22.tar.xz linux-1a5bae25e3cf95c4e83a97f87a6b5280d9acbb22.zip | |
mm/vmstat: add events for THP migration without split
Add following new vmstat events which will help in validating THP
migration without split. Statistics reported through these new VM events
will help in performance debugging.
1. THP_MIGRATION_SUCCESS
2. THP_MIGRATION_FAILURE
3. THP_MIGRATION_SPLIT
In addition, these new events also update normal page migration statistics
appropriately via PGMIGRATE_SUCCESS and PGMIGRATE_FAILURE. While here,
this updates current trace event 'mm_migrate_pages' to accommodate now
available THP statistics.
[akpm@linux-foundation.org: s/hpage_nr_pages/thp_nr_pages/]
[ziy@nvidia.com: v2]
Link: http://lkml.kernel.org/r/C5E3C65C-8253-4638-9D3C-71A61858BB8B@nvidia.com
[anshuman.khandual@arm.com: s/thp_nr_pages/hpage_nr_pages/]
Link: http://lkml.kernel.org/r/1594287583-16568-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Zi Yan <ziy@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Link: http://lkml.kernel.org/r/1594080415-27924-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/vm')
| -rw-r--r-- | Documentation/vm/page_migration.rst | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/Documentation/vm/page_migration.rst b/Documentation/vm/page_migration.rst index 1d6cd7db4e43..68883ac485fa 100644 --- a/Documentation/vm/page_migration.rst +++ b/Documentation/vm/page_migration.rst @@ -253,5 +253,32 @@ which are function pointers of struct address_space_operations. PG_isolated is alias with PG_reclaim flag so driver shouldn't use the flag for own purpose. +Monitoring Migration +===================== + +The following events (counters) can be used to monitor page migration. + +1. PGMIGRATE_SUCCESS: Normal page migration success. Each count means that a + page was migrated. If the page was a non-THP page, then this counter is + increased by one. If the page was a THP, then this counter is increased by + the number of THP subpages. For example, migration of a single 2MB THP that + has 4KB-size base pages (subpages) will cause this counter to increase by + 512. + +2. PGMIGRATE_FAIL: Normal page migration failure. Same counting rules as for + _SUCCESS, above: this will be increased by the number of subpages, if it was + a THP. + +3. THP_MIGRATION_SUCCESS: A THP was migrated without being split. + +4. THP_MIGRATION_FAIL: A THP could not be migrated nor it could be split. + +5. THP_MIGRATION_SPLIT: A THP was migrated, but not as such: first, the THP had + to be split. After splitting, a migration retry was used for it's sub-pages. + +THP_MIGRATION_* events also update the appropriate PGMIGRATE_SUCCESS or +PGMIGRATE_FAIL events. For example, a THP migration failure will cause both +THP_MIGRATION_FAIL and PGMIGRATE_FAIL to increase. + Christoph Lameter, May 8, 2006. Minchan Kim, Mar 28, 2016. |