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h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=BkptlubX345IW5aVCldqDNKuHbxUB1kJVmDDFs12+3s9hWGiS4nOhdxbnwGFTlL4c b0MUodgMFZkx7kX/z9mbw7HPggvGOg3lZ2gaXzro0cX9o4wPtmHcZVqdFb25kH6p+r XGr6FVQkDaYsRIcMTIPKTN/TE3YPPVeYWHuEroow= Date: Fri, 8 Dec 2023 11:58:21 -0800 From: Andrew Morton To: Nhat Pham Cc: tj@kernel.org, lizefan.x@bytedance.com, hannes@cmpxchg.org, cerasuolodomenico@gmail.com, yosryahmed@google.com, sjenning@redhat.com, ddstreet@ieee.org, vitaly.wool@konsulko.com, mhocko@kernel.org, roman.gushchin@linux.dev, shakeelb@google.com, muchun.song@linux.dev, hughd@google.com, corbet@lwn.net, konrad.wilk@oracle.com, senozhatsky@chromium.org, rppt@kernel.org, linux-mm@kvack.org, kernel-team@meta.com, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, david@ixit.cz, chrisl@kernel.org Subject: Re: [PATCH v6] zswap: memcontrol: implement zswap writeback disabling Message-Id: <20231208115821.402176c9e37ab11470a8656d@linux-foundation.org> In-Reply-To: References: <20231207192406.3809579-1-nphamcs@gmail.com> <20231207141142.307745be167d044b0eec1b42@linux-foundation.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 3FDD6A001E X-Stat-Signature: hodynhfgez8scfkude3dty1w34bzumg6 X-Rspam-User: X-HE-Tag: 1702065507-340802 X-HE-Meta: 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 dj0yHy1J 37lF0VKA6CWVpbcOI08DjA+OPlIfBxDh7G0WFqYKZK6L8WrnaxH+TPbAmnGT1s/qLDJkgeLirqByYnLjDDgD0PE0KEGczNp65NzTtFH7OamK22Z+NVtaGcV2uoDhO9uVuMrgcsMOE8vRUfTfaVEzXxxJ2Y2foTRHz9jsi2SGlXFZ0rKhFA/e9agqr1Y50mgE4ZRyDrzXK0BwgPJ0deRWMqjc8PPG0tBI69LdBcpYxorf8HZTRxcfT9FWKSNGHY9ejibjw 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: List-Subscribe: List-Unsubscribe: On Thu, 7 Dec 2023 17:14:22 -0800 Nhat Pham wrote: > > I don't have any concrete numbers though - any numbers I can pull out > > are from highly artificial tasks that only serve to test the > > correctness aspect of the implementation. zswap.writeback disablement > > would of course be faster in these situations (up to 33%!!!!) - but > > that's basically just saying HDD is slow. Which is not very > > informative or surprising, so I did not include it in the changelog. > > For instance, on a server with HDD, I allocate memories and populate > them with random values (so that zswap store will always fail), and > specify memory.high low enough to trigger reclaim. The time it takes > to allocate the memories and just read through it a couple of times > (doing silly things like computing the values' average etc.): > > zswap.writeback disabled: > real 0m30.537s > user 0m23.687s > sys 0m6.637s > 0 pages swapped in > 0 pages swapped out > > zswap.writeback enabled: > real 0m45.061s > user 0m24.310s > sys 0m8.892s > 712686 pages swapped in > 461093 pages swapped out > > (the last two lines are from vmstat -s). I pasted that also.