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| author | Johannes Weiner <hannes@cmpxchg.org> | 2022-10-26 14:01:33 -0400 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2022-11-30 15:58:41 -0800 |
| commit | 57e9cc50f4dd926d6c38751799d25cad89fb2bd9 (patch) | |
| tree | 35b891caefd466c2c7f976a2f56d6485d1a44013 /mm/khugepaged.c | |
| parent | 1b0166387586cae69d7da783f0a4521864534aad (diff) | |
| download | lwn-57e9cc50f4dd926d6c38751799d25cad89fb2bd9.tar.gz lwn-57e9cc50f4dd926d6c38751799d25cad89fb2bd9.zip | |
mm: vmscan: split khugepaged stats from direct reclaim stats
Direct reclaim stats are useful for identifying a potential source for
application latency, as well as spotting issues with kswapd. However,
khugepaged currently distorts the picture: as a kernel thread it doesn't
impose allocation latencies on userspace, and it explicitly opts out of
kswapd reclaim. Its activity showing up in the direct reclaim stats is
misleading. Counting it as kswapd reclaim could also cause confusion when
trying to understand actual kswapd behavior.
Break out khugepaged from the direct reclaim counters into new
pgsteal_khugepaged, pgdemote_khugepaged, pgscan_khugepaged counters.
Test with a huge executable (CONFIG_READ_ONLY_THP_FOR_FS):
pgsteal_kswapd 1342185
pgsteal_direct 0
pgsteal_khugepaged 3623
pgscan_kswapd 1345025
pgscan_direct 0
pgscan_khugepaged 3623
Link: https://lkml.kernel.org/r/20221026180133.377671-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Eric Bergen <ebergen@meta.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/khugepaged.c')
| -rw-r--r-- | mm/khugepaged.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 3703a56571c1..9c111273bbf9 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -2577,6 +2577,11 @@ void khugepaged_min_free_kbytes_update(void) mutex_unlock(&khugepaged_mutex); } +bool current_is_khugepaged(void) +{ + return kthread_func(current) == khugepaged; +} + static int madvise_collapse_errno(enum scan_result r) { /* |