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AJvYcCXfNxcKL3v8GDZ0fzuDsY/B57gDIBUoJBu0De4frfqV1Kq1X91EpP8wnfFkjQBzZDsUGwatZPelaQ==@kvack.org X-Gm-Message-State: AOJu0YylAw5KlFn/4AVLk7/ZkWRZrrZaqbX9CA+Q4zmYfx9HRg5NV3mW AI+UKD2RJr/kJRmwx+24dFRUbY7KWf6c4VqoQPXMzPH6eeCZcvMD X-Google-Smtp-Source: AGHT+IH5idc+duKEBmcHZ8WCavEtCgrW2+wGsc3I6OeXvDX0AWBqaokS1ncGgHEjyWAUqVtWcbcVwQ== X-Received: by 2002:a05:6a00:2308:b0:721:19bc:4bf4 with SMTP id d2e1a72fcca58-724bed5a66amr8103271b3a.23.1732184450990; Thu, 21 Nov 2024 02:20:50 -0800 (PST) Received: from localhost.localdomain ([43.154.34.99]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-724befa6167sm3219860b3a.131.2024.11.21.02.20.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Nov 2024 02:20:50 -0800 (PST) From: Jim Zhao To: jack@suse.cz, akpm@linux-foundation.org Cc: jimzhao.ai@gmail.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, shikemeng@huaweicloud.com, willy@infradead.org Subject: Re: [PATCH v2] mm/page-writeback: Raise wb_thresh to prevent write blocking with strictlimit Date: Thu, 21 Nov 2024 18:20:47 +0800 Message-Id: <20241121102047.610700-1-jimzhao.ai@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20241120115731.gzxozbnb6eazhil7@quack3> References: <20241120115731.gzxozbnb6eazhil7@quack3> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 8C5EF4000C X-Rspamd-Server: rspam11 X-Stat-Signature: dpokcjhhf3e1ssyrrpcbqpmj8rwnt7g3 X-HE-Tag: 1732184379-594023 X-HE-Meta: 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 1xvZU/0S 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000946, 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 Tue 19-11-24 20:29:22, Jim Zhao wrote: > > Thanks, Jan, I just sent patch v2, could you please review it ? > > Yes, the patch looks good to me. > > > > > And I found the debug info in the bdi stats. > > The BdiDirtyThresh value may be greater than DirtyThresh, and after > > applying this patch, the value of BdiDirtyThresh could become even > > larger. > > > > without patch: > > --- > > root@ubuntu:/sys/kernel/debug/bdi/8:0# cat stats > > BdiWriteback: 0 kB > > BdiReclaimable: 96 kB > > BdiDirtyThresh: 1346824 kB > > But this is odd. The machine appears to have around 3GB of memory, doesn't > it? I suspect this is caused by multiple cgroup-writeback contexts > contributing to BdiDirtyThresh - in fact I think the math in > bdi_collect_stats() is wrong as it is adding wb_thresh() calculated based > on global dirty_thresh for each cgwb whereas it should be adding > wb_thresh() calculated based on per-memcg dirty_thresh... You can have a > look at /sys/kernel/debug/bdi/8:0/wb_stats file which should have correct > limits as far as I'm reading the code. Thanks for review! Yes, It should be caused by multiple cgroup-writeback with bdi_collect_stats issue. @Andrew, I sent patch v2 according Jan's suggestion. Since patch v1 already in tree. So I sent out the diff of v1 -> v2: https://lore.kernel.org/all/20241121100539.605818-1-jimzhao.ai@gmail.com/ Could you please review it, thanks! Jim Zhao