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Fri, 07 Jun 2024 04:20:58 -0700 (PDT) Received: from google.com ([2401:fa00:8f:203:bd91:9a1b:54a5:7a73]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-703fd3b187fsm2392521b3a.85.2024.06.07.04.20.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 07 Jun 2024 04:20:57 -0700 (PDT) Date: Fri, 7 Jun 2024 20:20:52 +0900 From: Sergey Senozhatsky To: Nhat Pham Cc: Sergey Senozhatsky , Chengming Zhou , Yosry Ahmed , Erhard Furtner , Yu Zhao , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Johannes Weiner , Minchan Kim , "Vlastimil Babka (SUSE)" Subject: Re: kswapd0: page allocation failure: order:0, mode:0x820(GFP_ATOMIC), nodemask=(null),cpuset=/,mems_allowed=0 (Kernel v6.5.9, 32bit ppc) Message-ID: <20240607112052.GA479513@google.com> References: <20240604231019.18e2f373@yea> <20240606010431.2b33318c@yea> <20240606043156.GC11718@google.com> <6335c05d-9493-4b03-85a7-f2dd91db9451@linux.dev> <20240606054334.GD11718@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: B9E554000D X-Stat-Signature: bewwg61i69pwp75155mw8npwqjgmu3as X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1717759259-309070 X-HE-Meta: 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 /4Vi+AsS jWDiF9oaGJnfw2Qqhyp46lpxNn6fmF1RH3XJXyzzNwb3efFSSgF3GkGnIqhFlqBWIeDjVAC81C5gXNPcpMpWNY+JxfN82hl9Tv2l0S7R3kH0bW0tVhXFl8PM+DJh80h7GqS7ZgEj1lxdumFgqzuVQltSLcyfPgguF43IShxWMPkwCjw6sahH/dn5qlcAlsDjRbwGjsVzrgO2+VEt5UsuGTaxlSnWw+9VEJE/64SYkNch3zDj1tVECtnr5NyaOwORPYUzVuQuysFDQqo95b+CEWpxn2F20G7AvODyzCeIheyt2yWjmSmI77sLoZ746iwEb9/sA6HDO30vpnyelEVfIjjUsScTj2Q03ZUi6Td9hypof/YToRd3oXeW+r20qLfw6dsXT1HMQ/QKU0cp3tiG4LRFUMBqPz5ETZIWkssNDJtTEjNV8ihYQItH0fA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.001319, 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 (24/06/07 10:40), Nhat Pham wrote: > Personally, I'm not super convinced about class locks. We're > essentially relying on the post-compression size of the data to > load-balance the queries - I can imagine a scenario where a workload > has a concentrated distribution of post-compression data (i.e its > pages are compressed to similar-ish sizes), and we're once again > contending for a (few) lock(s) again. > > That said, I'll let the data tell the story :) We don't need a perfect > solution, just a good enough solution for now. Speaking of size class locks: One thing to mention is that zsmalloc merges size classes, we never have documented/claimed 256 size classe, the actual number is always much much lower. Each such "cluster" (merged size classes) holds a range of objects' sizes (e.g. 3504-3584 bytes). The wider the cluster's size range the more likely the (size class) lock contention is. Setting CONFIG_ZSMALLOC_CHAIN_SIZE to 10 or higher makes zsmalloc pool to be configured with more size class clusters (which means that clusters hold narrower size intervals).