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Wed, 26 Apr 2023 15:10:14 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id H9TANdY+SWR3eQAAMHmgww (envelope-from ); Wed, 26 Apr 2023 15:10:14 +0000 Message-ID: Date: Wed, 26 Apr 2023 17:10:14 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: [PATCH] Revert "Revert "mm/compaction: fix set skip in fast_find_migrateblock"" Content-Language: en-US To: Baolin Wang , akpm@linux-foundation.org Cc: mgorman@techsingularity.net, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <3576e3520c044beb2a81860aecb2d4f597089300.1682521303.git.baolin.wang@linux.alibaba.com> From: Vlastimil Babka In-Reply-To: <3576e3520c044beb2a81860aecb2d4f597089300.1682521303.git.baolin.wang@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 8DA9A180032 X-Rspamd-Server: rspam01 X-Stat-Signature: dy9nsdsgno187aw8q3prkes3yfszrppe X-HE-Tag: 1682521816-400043 X-HE-Meta: U2FsdGVkX19vOlkuJjFk6GNLGne5YQkfAfmoXl5FKlkQIgABIboQN9vllk/lnS0CqIgfN1sEpeNvzOOUaSfGZ8mKOHEygnUMZHX1BdF+pn9TFnM5TYztN23C/kry3Pa852o2cigIvNXIvzwsLeaYBfP74qCK2XclfGuyT9rYgheQLLMHEOu0R9hxqx2i6xKaAWji2KEowLNtdijlsDY5Oddg8qMGD+PfYSc3NZipYhwaoRwb06iviLvTDnxDc5BjV2zdtGb701nyy8YXVlT/mkDP1IrT+BzEq3iqxNb0YafezrZAAd+r2ntNx2+lBPcP6TZtTB5jK1e+K2acn8q7OIpRS5VyJ/SrRSYRMeJJBkpP2ZJIxAvURHTQyD6SNNSh3bL8nb+ZlnXfNh1Gd0RNNDMURBdP38EjyT6mnEyudITGLRTvz28bw3B11Isjv6CXHVVux0ZWP2hWUCkY8ZSXdThwZd4HCzkelr3Q5cQCybbhuPnSAPp4UzcD+63OxWfkVjTWKkEBOy3Js4psknZdaZOYtDKbW6O+x/vnwe4jSUL6wny7aUE2mSZawbXc+QM0QTQbbrG1EftwzOTm+yVa3wdLaSgbXCkHhUPSMCHCxINOBnsQ/Bir8QQ7bQQOtrlvLVEk2dIXINmpNfQyHEEnrtgFtzg1lAW6OJZNmXmsRe0/MIO+9yCbc3P7R7WVZw8PMMsp72bsQNcPx6jXLz451kpF5FYtVp4yUM7PtjcqQhwnGEFICoKp0tf6knULWchsTtprRCvmJzASgreZOUHFpcQrnO6FefXj1HDZddhhzPVLSBZHy+0E2suqIcxiTz7FVANT6Y1o+Yadd0LCnEyv6snq+Thf/4oRKMPEFdRMSWbzZX5MKKo+dO67spdDdM0Kt8QHsA/QxnYNr2Cg2AniY3wn8SVBm/o8OZCYWTZpX/k1yy+246uR9xLrSZaC7r1Dgf87x7Vbl2FPd/lfril TBeR/GAG wDa4C0dyteE/cTNux+XbRNUQJp3J8l8Y5mW4JkhtQZxa6NR5rAzUINMUI6B+2/XrepKz/uSD0xC0x22Jrhog/1EglFTag2tyx7fsuerhIVKSAmw0BKAVIX9Gwi8RIkdWLopQh4o5KaUaJhv5D1HG5w1JsQ0yGtVs7HYagQ0NJnQET/kKCwPZeY9fUyposOWS2IL8QZw3XPVeaIxzF0w9bmB17PcF6rbIGYFw3JCXYVweSghisbX+viTouzqzVQ7e3FIubA/jOCxKNZ94= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 4/26/23 17:03, Baolin Wang wrote: > This reverts commit 95e7a450b8190673675836bfef236262ceff084a. > > When I tested thpscale with v6.3 kernel, I found the compaction efficiency > had a great regression compared to v6.2-rc1 kernel. See below numbers: > v6.2-rc v6.3 > Percentage huge-3 81.35 ( 0.00%) 32.97 ( -59.47%) > Percentage huge-5 89.92 ( 0.00%) 41.70 ( -53.63%) > Percentage huge-7 92.41 ( 0.00%) 34.08 ( -63.12%) > Percentage huge-12 90.29 ( 0.00%) 41.10 ( -54.49%) > Percentage huge-18 82.38 ( 0.00%) 41.24 ( -49.95%) > Percentage huge-24 80.34 ( 0.00%) 35.99 ( -55.20%) > Percentage huge-30 88.90 ( 0.00%) 44.20 ( -50.28%) > Percentage huge-32 90.69 ( 0.00%) 79.57 ( -12.25%) > > Ops Compaction stalls 113790.00 207099.00 > Ops Compaction success 33983.00 19488.00 > Ops Compaction failures 79807.00 187611.00 > Ops Compaction efficiency 29.86 9.41 > > After some investigation, I found the commit 95e7a450b819 > ("Revert mm/compaction: fix set skip in fast_find_migrateblock") caused > the regression. This commit revert the commit 7efc3b726103 ("mm/compaction: > fix set skip in fast_find_migrateblock") to fix a CPU stalling issue, which > is caused by compaction stucked in repeating fast_find_migrateblock(). > > And now the compaction stalling issue is addressed by commit cfccd2e63e7e > ("mm, compaction: finish pageblocks on complete migration failure"). So IIRC at that time I was pointing out some scenarios that could make the problem appear even after that commit, and we wanted to revisit that when Mel is back. > we should revert the temporary fix by commit 95e7a450b819, since the > fast pfn found by fast_find_migrateblock() really can help to isolate > some migratable pages. So thanks for the reminder, yet we should make sure the fix is complete before removing the workaround. > After reverting the commit, the regression has gone. > v6.2-rc1 v6.3 v6.3_patched > Percentage huge-3 81.35 ( 0.00%) 32.97 ( -59.47%) 87.78 ( 7.90%) > Percentage huge-5 89.92 ( 0.00%) 41.70 ( -53.63%) 89.68 ( -0.27%) > Percentage huge-7 92.41 ( 0.00%) 34.08 ( -63.12%) 85.89 ( -7.05%) > Percentage huge-12 90.29 ( 0.00%) 41.10 ( -54.49%) 94.10 ( 4.22%) > Percentage huge-18 82.38 ( 0.00%) 41.24 ( -49.95%) 85.06 ( 3.25%) > Percentage huge-24 80.34 ( 0.00%) 35.99 ( -55.20%) 84.38 ( 5.02%) > Percentage huge-30 88.90 ( 0.00%) 44.20 ( -50.28%) 95.54 ( 7.48%) > Percentage huge-32 90.69 ( 0.00%) 79.57 ( -12.25%) 92.30 ( 1.78%) > > Signed-off-by: Baolin Wang > --- > mm/compaction.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/mm/compaction.c b/mm/compaction.c > index 33650541bebc..567c8d41d01e 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -1860,7 +1860,6 @@ 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; > } > }