Re: [PATCH v4 1/4] mm/pageblock: mitigation cmpxchg false sharing in pageblock flags

Alex Shi
2020-09-03T08:40:54Z

在 2020/9/3 下午4:32, Alex Shi 写道:
>>
> I have run thpscale with 'always' defrag setting of THP. The Amean stddev is much
> larger than a very little average run time reducing.
>
> But the left patch 4 could show the cmpxchg retry reduce from thousands to hundreds
> or less.
>
> Subject: [PATCH v4 4/4] add cmpxchg tracing

It's a typical result with the patchset:

Performance counter stats for './run-mmtests.sh -c configs/config-workload-thpscale pageblock-c':

9,564 compaction:mm_compaction_isolate_migratepages
6,430 compaction:mm_compaction_isolate_freepages
5,287 compaction:mm_compaction_migratepages
45,299 compaction:mm_compaction_begin
45,299 compaction:mm_compaction_end
30,557 compaction:mm_compaction_try_to_compact_pages
95,540 compaction:mm_compaction_finished
149,379 compaction:mm_compaction_suitable
0 compaction:mm_compaction_deferred
0 compaction:mm_compaction_defer_compaction
3,949 compaction:mm_compaction_defer_reset
0 compaction:mm_compaction_kcompactd_sleep
0 compaction:mm_compaction_wakeup_kcompactd
0 compaction:mm_compaction_kcompactd_wake
68 pageblock:hit_cmpxchg

113.570974583 seconds time elapsed

14.664451000 seconds user
96.847116000 seconds sys

It's 5.9-rc2 base kernel result:

Performance counter stats for './run-mmtests.sh -c configs/config-workload-thpscale rc2-e':

15,920 compaction:mm_compaction_isolate_migratepages
20,523 compaction:mm_compaction_isolate_freepages
9,752 compaction:mm_compaction_migratepages
27,773 compaction:mm_compaction_begin
27,773 compaction:mm_compaction_end
16,391 compaction:mm_compaction_try_to_compact_pages
62,809 compaction:mm_compaction_finished
69,821 compaction:mm_compaction_suitable
0 compaction:mm_compaction_deferred
0 compaction:mm_compaction_defer_compaction
7,875 compaction:mm_compaction_defer_reset
0 compaction:mm_compaction_kcompactd_sleep
0 compaction:mm_compaction_wakeup_kcompactd
0 compaction:mm_compaction_kcompactd_wake
1,208 pageblock:hit_cmpxchg

116.440414591 seconds time elapsed

15.326913000 seconds user
103.752758000 seconds sys