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[124.209.188.1]) by smtp.gmail.com with ESMTPSA id m2-20020a17090aab0200b0024677263e36sm8675229pjq.43.2023.04.18.04.24.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 Apr 2023 04:24:55 -0700 (PDT) Date: Tue, 18 Apr 2023 20:24:50 +0900 From: Sergey Senozhatsky To: Yosry Ahmed Cc: Andrew Morton , Sergey Senozhatsky , Minchan Kim , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCHv2] zsmalloc: allow only one active pool compaction context Message-ID: <20230418112450.GT25053@google.com> References: <20230417135420.1836741-1-senozhatsky@chromium.org> <20230417174131.44de959204814209ef73e53e@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 323281A0017 X-Rspam-User: X-Stat-Signature: c3bdkuzdyg6qfqjwookfimzf7xaasng5 X-HE-Tag: 1681817096-848579 X-HE-Meta: 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 H53xoE0Y g/ah2GOCYJF38KYpLzHRl5DsHJ/SP8febLmYXeDRbBOze5SU70bsA4Lm3H6dHDr9RE0TyRbna7t5796CdQp3iPrn8nzhSfa8qXPi0uxD3xATTPae2DPGiWtFElaAOg/5n79U+diDQok42dpo+KEKbdSMXJFMmrkKBpwX+PDYVFmxvwmGp9O1YsSz5HQ0i0+6aCn+jxVG15l+rnW3C55TgwOxZ2wNl54+cz5wIpYrmTo9MHzAJY8bVUrwhuRCvE/jESK1hWjjKCD3srTYWZ1qjVeqXJy6qMMoCMaT4CpP65ICzK+M+xZQNvTGRCx3Se7jAU7PpYCIF9tW/j4p8lvIpLUOGNNSc1AkyUIYHCcAQg31U+hQ= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000053, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On (23/04/17 19:53), Yosry Ahmed wrote: > > As for this patch, I personally do not observe a lot of compaction in > our production environment, and allowing one thread to perform > compaction while others move on with their lives can be better than > having all of them continuously contending for the pool->lock, which > means more contention with ~all zsmalloc operations, not just > concurrent compactors. I can't say for sure that this is an > improvement, but I *believe* it is. Looking at one of ChromeOS memory-pressure tests, I see that sometimes (albeit rarely) we can have up to 9 parallel zspool compaction contexts, perhaps a little bit too many for a 12 CPUs laptop: [ 2159.378827] zsmalloc: ctx #1 chrome -> zs_compact() [ 2159.379002] zsmalloc: ctx #2 Chrome_ChildIOT -> zs_compact() [ 2159.379120] zsmalloc: ctx #3 chrome -> zs_compact() [ 2159.379135] zsmalloc: ctx #4 chrome -> zs_compact() [ 2159.379213] zsmalloc: ctx #5 chrome -> zs_compact() [ 2159.379271] zsmalloc: ctx #6 chrome -> zs_compact() [ 2159.379276] zsmalloc: ctx #7 chrome -> zs_compact() [ 2159.382786] zsmalloc: ctx #8 chrome -> zs_compact() [ 2159.432153] zsmalloc: ctx #9 kswapd0 -> zs_compact()