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AJvYcCXMbecsTdpUA4Cd31ZSI2UyCPSsaP3nIFr0b8SGIS3c3HE4tLokPDqmzWuuGXngQwzb8uakEw+Jwg==@kvack.org X-Gm-Message-State: AOJu0YwyDqmHJA3XlIV+I1mqdsUG/JyQsXLF+3tJn6Jtfk9ubUbIR+DD fMr73dyT158f0OehhUH6iQd1nKFTU3QrWZeA4tv9y0Z2HB6KvkPQ4rM8khzF3M0= X-Google-Smtp-Source: AGHT+IHJqyXqdkePK3CZZGGmyrtJ+p/ACo/Iy9jG5PrYhxG0iafEwE9SELoDNXGFcFXpHUKwFp3/Ug== X-Received: by 2002:a05:6214:5992:b0:6c5:7ed0:194a with SMTP id 6a1803df08f44-6cb1dd09a19mr46739536d6.2.1727272433156; Wed, 25 Sep 2024 06:53:53 -0700 (PDT) Received: from localhost ([2603:7000:c01:2716:da5e:d3ff:fee7:26e7]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6cb0f554371sm16411466d6.80.2024.09.25.06.53.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Sep 2024 06:53:52 -0700 (PDT) Date: Wed, 25 Sep 2024 09:53:48 -0400 From: Johannes Weiner To: "Sridhar, Kanchana P" Cc: Yosry Ahmed , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "nphamcs@gmail.com" , "chengming.zhou@linux.dev" , "usamaarif642@gmail.com" , "shakeel.butt@linux.dev" , "ryan.roberts@arm.com" , "Huang, Ying" , "21cnbao@gmail.com" <21cnbao@gmail.com>, "akpm@linux-foundation.org" , "Zou, Nanhai" , "Feghali, Wajdi K" , "Gopal, Vinodh" Subject: Re: [PATCH v7 5/8] mm: zswap: Compress and store a specific page in a folio. Message-ID: <20240925135348.GB875661@cmpxchg.org> References: <20240924011709.7037-1-kanchana.p.sridhar@intel.com> <20240924011709.7037-6-kanchana.p.sridhar@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 4377A40007 X-Stat-Signature: tbaz7zr9eb94b9yta9nsupajnbukbfta X-HE-Tag: 1727272434-829996 X-HE-Meta: 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 nwGdUnje 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 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 Wed, Sep 25, 2024 at 01:49:03AM +0000, Sridhar, Kanchana P wrote: > > From: Yosry Ahmed > > I think it's more correct and efficient to update the atomic once > > after all the pages are successfully compressed and stored. > > Actually this would need to co-relate with the limits checking strategy, > because the atomic is used there and needs to be as accurate as possible. For the limit checks, we use the zpool counters, not zswap_stored_pages. zswap_stored_pages is used in the zswap shrinker to guesstimate pressure, so it's likely a good thing to only count entries that are expected to stay, and not account the ones that might fail just yet. > As far as the vmstat 'zswpout', the reason I left it as-is in my patchset > was to be more indicative of the actual zswpout compute events that > occurred (for things like getting the compressions count), regardless > of whether or not the overall mTHP store was successful. If this vmstat > needs to reflect only successful zswpout events (i.e., represent the zswap > usage), I can fix it by updating it once only if the mTHP is stored successfully. Yeah, that's fine as well. I would suggest batching them both at the end of zswap_store().