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

[Alex Shi]

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