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| author | William Lam <william.lam@bytedance.com> | 2022-07-11 21:28:06 +0100 |
|---|---|---|
| committer | akpm <akpm@linux-foundation.org> | 2022-07-29 18:07:14 -0700 |
| commit | b717d6b93b54ec2a2a7d3bb7268d3ff847cc54c5 (patch) | |
| tree | f98442e0274b06c901382473cd8471ca9af029c3 /mm | |
| parent | ac3ced5fc12fb3d7268054485cbc36441c05cf24 (diff) | |
| download | linux-b717d6b93b54ec2a2a7d3bb7268d3ff847cc54c5.tar.gz | |
mm: compaction: include compound page count for scanning in pageblock isolation
The number of scanned pages can be lower than the number of isolated pages when isolating mirgratable or free pageblock. The metric is being reported in trace event and also used in vmstat. some example output from trace where it shows nr_taken can be greater than nr_scanned: Produced by kernel v5.19-rc6 kcompactd0-42 [001] ..... 1210.268022: mm_compaction_isolate_migratepages: range=(0x107ae4 ~ 0x107c00) nr_scanned=265 nr_taken=255 [...] kcompactd0-42 [001] ..... 1210.268382: mm_compaction_isolate_freepages: range=(0x215800 ~ 0x215a00) nr_scanned=13 nr_taken=128 kcompactd0-42 [001] ..... 1210.268383: mm_compaction_isolate_freepages: range=(0x215600 ~ 0x215680) nr_scanned=1 nr_taken=128 mm_compaction_isolate_migratepages does not seem to have this behaviour, but for the reason of consistency, nr_scanned should also be taken care of in that side. This behaviour is confusing since currently the count for isolated pages takes account of compound page but not for the case of scanned pages. And given that the number of isolated pages(nr_taken) reported in mm_compaction_isolate_template trace event is on a single-page basis, the ambiguity when reporting the number of scanned pages can be removed by also including compound page count. Link: https://lkml.kernel.org/r/20220711202806.22296-1-william.lam@bytedance.com Signed-off-by: William Lam <william.lam@bytedance.com> Reviewed-by: Punit Agrawal <punit.agrawal@bytedance.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/compaction.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/compaction.c b/mm/compaction.c index cd029ab03d0e..d024d18e0b5c 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -616,6 +616,7 @@ static unsigned long isolate_freepages_block(struct compact_control *cc, break; set_page_private(page, order); + nr_scanned += isolated - 1; total_isolated += isolated; cc->nr_freepages += isolated; list_add_tail(&page->lru, freelist); @@ -1101,6 +1102,7 @@ isolate_success: isolate_success_no_list: cc->nr_migratepages += compound_nr(page); nr_isolated += compound_nr(page); + nr_scanned += compound_nr(page) - 1; /* * Avoid isolating too much unless this block is being @@ -1504,6 +1506,7 @@ fast_isolate_freepages(struct compact_control *cc) if (__isolate_free_page(page, order)) { set_page_private(page, order); nr_isolated = 1 << order; + nr_scanned += nr_isolated - 1; cc->nr_freepages += nr_isolated; list_add_tail(&page->lru, &cc->freepages); count_compact_events(COMPACTISOLATED, nr_isolated); |