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Wed, 12 Feb 2025 18:18:23 -0800 (PST) Received: from google.com ([2401:fa00:8f:203:3ed3:97ce:5f5f:1f61]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-220d536738csm2123775ad.68.2025.02.12.18.18.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 Feb 2025 18:18:22 -0800 (PST) Date: Thu, 13 Feb 2025 11:18:17 +0900 From: Sergey Senozhatsky To: Yosry Ahmed Cc: Sergey Senozhatsky , Andrew Morton , Minchan Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Kairui Song Subject: Re: [PATCHv4 14/17] zsmalloc: make zspage lock preemptible Message-ID: References: <6vtpamir4bvn3snlj36tfmnmpcbd6ks6m3sdn7ewmoles7jhau@nbezqbnoukzv> <6uhsj4bckhursiblkxe54azfgyqal6tq2de3lpkxw6omkised6@uylodcjruuei> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: BA70F100002 X-Stat-Signature: n6973z8n86bk4oigatynxsnek6c9jta4 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1739413104-381849 X-HE-Meta: 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 EWd58OkW Ii0Y4UyVXKHa+S6OGP0jW907f+eivo2fM1Eoxra0klThoOdHw4Zj/rXCwTxf0+oqU+a97y8+8vSENeAihEoQuM9cpVF+AQtnbJfwhqTBEhKws052xOTtl3lV/RBYK1+qye0E/MhcgP8aBlvn4g/yFLO1Uofkm7N2JrC5ozK/jO/hWOD1THWlYvPSxUqlc1Bpom8IEd7konmhFVYrU5yIzU2r2Q6dhyGHpGd3fko0Fr8UYBOBSTbm/WNCOkX5S3XG16PQvtFT7EPKfQ9yHZz9GsEb3x9IiY+f+NCGOLjPq8fuLS6SmtViy0YaRu6idWRxbPcn83B+caeeYAY5Qp+nK7/N2qE7LTQ4XFLDxuzkaR9PU/M0= X-Bogosity: Ham, tests=bogofilter, spamicity=0.026704, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On (25/02/12 15:35), Yosry Ahmed wrote: > > Difference at 95.0% confidence > > -1.03219e+08 +/- 55308.7 > > -27.9705% +/- 0.0149878% > > (Student's t, pooled s = 58864.4) > > Thanks for sharing these results, but I wonder if this will capture > regressions from locking changes (e.g. a lock being preemtible)? IIUC > this is counting the instructions executed in these paths, and that > won't change if the task gets preempted. Lock contention may be captured > as extra instructions, but I am not sure we'll directly see its effect > in terms of serialization and delays. Yeah.. > I think we also need some high level testing (e.g. concurrent > swapins/swapouts) to find that out. I think that's what Kairui's testing > covers. I do a fair amount of high-level testing: heavy parallel (make -j36 and parallel dd) workloads (multiple zram devices configuration - zram0 ext4, zram1 writeback device, zram2 swap) w/ and w/o lockdep. In addition I also run these workloads under heavy memory pressure (a 4GB VM), when oom-killer starts to run around with a pair of scissors. But it's mostly regression testing.