diff options
| author | Yang Yang <yang.yang29@zte.com.cn> | 2023-04-13 16:34:49 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-04-18 16:30:11 -0700 |
| commit | ed8f3f999e9270ccc542ac44e237e389a2687a9e (patch) | |
| tree | 01870b2febf6ec91ecfedf47a9c1ad9d54de7786 /mm/workingset.c | |
| parent | 1f6ab566cb3be9e8292e34b89e8be83d75aa232e (diff) | |
mm: workingset: update description of the source file
The calculation of workingset size is the core logic of handling refault,
it had been updated several times[1][2] after workingset.c was created[3].
But the description hadn't been updated accordingly, this mismatch may
confuse the readers. So we update the description to make it consistent
to the code.
[1] commit 34e58cac6d8f ("mm: workingset: let cache workingset challenge anon")
[2] commit aae466b0052e ("mm/swap: implement workingset detection for anonymous LRU")
[3] commit a528910e12ec ("mm: thrash detection-based file cache sizing")
Link: https://lkml.kernel.org/r/202304131634494948454@zte.com.cn
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/workingset.c')
| -rw-r--r-- | mm/workingset.c | 23 |
1 files changed, 17 insertions, 6 deletions
diff --git a/mm/workingset.c b/mm/workingset.c index 3025beee9b34..817758951886 100644 --- a/mm/workingset.c +++ b/mm/workingset.c @@ -111,9 +111,20 @@ * * NR_inactive + (R - E) <= NR_inactive + NR_active * - * which can be further simplified to + * If we have swap we should consider about NR_inactive_anon and + * NR_active_anon, so for page cache and anonymous respectively: * - * (R - E) <= NR_active + * NR_inactive_file + (R - E) <= NR_inactive_file + NR_active_file + * + NR_inactive_anon + NR_active_anon + * + * NR_inactive_anon + (R - E) <= NR_inactive_anon + NR_active_anon + * + NR_inactive_file + NR_active_file + * + * Which can be further simplified to: + * + * (R - E) <= NR_active_file + NR_inactive_anon + NR_active_anon + * + * (R - E) <= NR_active_anon + NR_inactive_file + NR_active_file * * Put into words, the refault distance (out-of-cache) can be seen as * a deficit in inactive list space (in-cache). If the inactive list @@ -130,14 +141,14 @@ * are no longer in active use. * * So when a refault distance of (R - E) is observed and there are at - * least (R - E) active pages, the refaulting page is activated - * optimistically in the hope that (R - E) active pages are actually + * least (R - E) pages in the userspace workingset, the refaulting page + * is activated optimistically in the hope that (R - E) pages are actually * used less frequently than the refaulting page - or even not used at * all anymore. * * That means if inactive cache is refaulting with a suitable refault * distance, we assume the cache workingset is transitioning and put - * pressure on the current active list. + * pressure on the current workingset. * * If this is wrong and demotion kicks in, the pages which are truly * used more frequently will be reactivated while the less frequently @@ -469,7 +480,7 @@ void workingset_refault(struct folio *folio, void *shadow) * don't activate pages that couldn't stay resident even if * all the memory was available to the workingset. Whether * workingset competition needs to consider anon or not depends - * on having swap. + * on having free swap space. */ workingset_size = lruvec_page_state(eviction_lruvec, NR_ACTIVE_FILE); if (!file) { |