Re: [PATCH v2] mm/compaction: fix set skip in fast_find_migrateblock

[Chuyi Zhou <zhouchuyi@bytedance.com>]

在 2022/7/13 上午10:23, Miaohe Lin 写道:
> On 2022/7/12 15:27, Zhou Chuyi wrote:
>> From: zhouchuyi <zhouchuyi@bytedance.com>
>>
>> When we successfully find a pageblock in
>> fast_find_migrateblock(), the block will be set
>> skip-flag through set_pageblock_skip().
>> However, when entering isolate_migratepages_block(),
>> the whole pageblock will be skipped due to the branch
>> 'if (!valid_page && IS_ALIGNED(low_pfn, pageblock_nr_pages))'.
>> Eventually we will goto isolate_abort and isolate nothing.
>> That cause fast_find_migrateblock useless.
>>
>> In this Patch, when we find a suitable pageblock in
>> fast_find_migrateblock, we do noting but let
>> isolate_migratepages_block to set skip flag to
>> the pageblock after scan it. Normally, we would
>> isolate some pages from the fast-find block.
>>
>> I use mmtest/thpscale-madvhugepage test it. Here
>> is the result:
>> 			    baseline		   patch
>> Amean     fault-both-1      1331.66 (   0.00%)     1261.04 *   5.30%*
>> Amean     fault-both-3      1383.95 (   0.00%)     1191.69 *  13.89%*
>> Amean     fault-both-5      1568.13 (   0.00%)     1445.20 *   7.84%*
>> Amean     fault-both-7      1819.62 (   0.00%)     1555.13 *  14.54%*
>> Amean     fault-both-12     1106.96 (   0.00%)     1149.43 *  -3.84%*
>> Amean     fault-both-18     2196.93 (   0.00%)     1875.77 *  14.62%*
>> Amean     fault-both-24     2642.69 (   0.00%)     2671.21 *  -1.08%*
>> Amean     fault-both-30     2901.89 (   0.00%)     2857.32 *   1.54%*
>> Amean     fault-both-32     3747.00 (   0.00%)     3479.23 *   7.15%*
>>
>> Fixs: 'commit 70b44595eafe9 ("mm, compaction: use free lists
>> to quickly locate a migration source")'
> 
> Thanks for your patch. Yet something to improve:
> 
> ./scripts/checkpatch.pl v2-mm-compaction-fix-set-skip-in-fast_find_migrateblock.patch
> ERROR: Please use git commit description style 'commit <12+ chars of sha1> ("<title line>")' - ie: 'commit 70b44595eafe ("mm, compaction: use free lists to quickly locate a migration source")'
> #101:
> Fixs: 'commit 70b44595eafe9 ("mm, compaction: use free lists
> to quickly locate a migration source")'
> 
> total: 1 errors, 0 warnings, 7 lines checked
> 
> NOTE: For some of the reported defects, checkpatch may be able to
>        mechanically convert to the typical style using --fix or --fix-inplace.
> 
> [PATCH v2] mm_compaction  fix set skip in fast_find_migrateblock.eml has style problems, please review.
> 
> NOTE: If any of the errors are false positives, please report
>        them to the maintainer, see CHECKPATCH in MAINTAINERS.
> 
> And remember runing get_maintainer.pl to get the right people before sending the patch:
> 
> ./scripts/get_maintainer.pl v2-mm-compaction-fix-set-skip-in-fast_find_migrateblock.patch
> Andrew Morton <akpm@linux-foundation.org> (maintainer:MEMORY MANAGEMENT)
> linux-mm@kvack.org (open list:MEMORY MANAGEMENT)
> linux-kernel@vger.kernel.org (open list)
> 
> BTW: It's not enforced but ~70 chars per line in commit log might be preferred.
Thanks for your help sincerely. It seems I should use "Fixes". However, 
I wonder to know why I run ./scripts/checkpatch.pl it shows :
total: 0 errors, 0 warnings, 7 lines checked
0001-mm-compaction-fix-set-skip-in-fast_find_migrateblock.patch has no 
  obvious style problems and is ready for submission.

I clone the kernel source from 
https://kernel.googlesource.com/pub/scm/linux/kernel/git/stable/linux-stable. 
Maby I should clone the source from another place ?
> 
>>
>> Signed-off-by: zhouchuyi <zhouchuyi@bytedance.com>
> 
> Thanks.
> 
>> ---
>>   mm/compaction.c | 1 -
>>   1 file changed, 1 deletion(-)
>>
>> diff --git a/mm/compaction.c b/mm/compaction.c
>> index 1f89b969c..a1a2b50c8 100644
>> --- a/mm/compaction.c
>> +++ b/mm/compaction.c
>> @@ -1852,7 +1852,6 @@ static unsigned long fast_find_migrateblock(struct compact_control *cc)
>>   					pfn = cc->zone->zone_start_pfn;
>>   				cc->fast_search_fail = 0;
>>   				found_block = true;
>> -				set_pageblock_skip(freepage);
>>   				break;
>>   			}
>>   		}
>>
>