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Mon, 10 Nov 2025 22:27:39 -0800 (PST) From: Leon Huang Fu To: tj@kernel.org Cc: akpm@linux-foundation.org, cgroups@vger.kernel.org, corbet@lwn.net, hannes@cmpxchg.org, jack@suse.cz, joel.granados@kernel.org, kyle.meyer@hpe.com, lance.yang@linux.dev, laoar.shao@gmail.com, leon.huangfu@shopee.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mclapinski@google.com, mhocko@kernel.org, mkoutny@suse.com, muchun.song@linux.dev, roman.gushchin@linux.dev, shakeel.butt@linux.dev Subject: Re: [PATCH mm-new v3] mm/memcontrol: Add memory.stat_refresh for on-demand stats flushing Date: Tue, 11 Nov 2025 14:27:30 +0800 Message-ID: <20251111062732.72880-1-leon.huangfu@shopee.com> X-Mailer: git-send-email 2.51.2 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 8DA2640002 X-Stat-Signature: 8h7p35j3ojbbdosg47x9rqbm7accmr9e X-HE-Tag: 1762842461-970473 X-HE-Meta: U2FsdGVkX1/Bmdr8+5uuURd4nyKxFMDntlGyww/Ucr5tKiceskehEwanAtRhxEl/bUcNUjOjnshVyzU7oEG6h/9xpvWAVQUPjDJZc2Ercn0IK13UjZh1qM/GoD365iXalP5Qs0zUpKeV6lacVVghEE9oO7MLzQ3ViGHCMhzlkaP475ENdWGgHJ7VvsJ1ybeXtn4E2tudsGEafBgwIP2cwUC6VYrFL3Yh6Oi8iqy9KxR++dKJgT/1sT8YBAaT/laqh6VCdmdwyV+rAdmKMLMwrVpD70Eqri5CfZctsy+JzM+UnW50VWsW+/WcCDW1VT52OFmReeKA4PqTkAL5ApUtArAgm3NUw5IhLLCKd+KYJligiCCn3N2uolyJFRnecZLtaP94Pdq0bTDWD7ijKxXXXN0IMzQeCgvuAdNMJxSxnIsZddE1VIxY9KnVdlnP/mw8UNitSD5y6xn5RWEhr51LexWfQdvJqhDalWFiHjgNj96F25GmxUXYQw7uChQ8XKlzM3VfEnT58g4/kDc097s8jts9bMAT38iUVuXZIZsN7gZxL5EvX3B8JS0LLt7K9D0vEwHMPtQV8FNrzyJVJw3oAr64GAWHTx19r5191fiChq/UJWZdG6OU1H9J6ncv+syl1uaVbdwkciXUSqEG4KeeGVtIyHB25XJK4g9iL7zzgWLcVMWfGG/M+ShcIAjU0ip8TqijMW2BfmOeOOBF+tO6diCjpjuv/sOIE76r57rBkAVCEVHenkiFmjVzqiM5cKs/Oe0P9Eg0cWIXfGyiL20YUMaZeC7FIY+5ssEb9+kp+Uzs9KCTfiDdwbrnn13AJ0Vo8TlcBowqNS0MimNRn9Hrs2pfmcxW3SoZyazT+m+6sYpBfi2AXkavaTGvQTmvj8Kv9uruJLPoi40yNcf851+n4EgUMxaVdGG9EB7uRkf/UqghNBZatVe4xeJSV04fP3uS/QZP+jYkA6TExd5rMJs ry0qGyfw wCMCwxcUQslhMUcid3F6Ue8nMBBt5SF+q/nwT65uQB/Fbe+d7tdsGfqEVXAt1vqY/KqwYmC0MlY9LKnFRD2eBvX8Tgbr6Nf2JaaTPxT9Dn9ukaWDK+m0qLFFHFrFySVS6SB6haADtljDK4cVLoYWdwpUd25Dl4/+kYxfetdA+cweJ0XHgEp2BRoQUQzLuI40ylKFxUWU3jbk0Rc28S3/O6926Ve92GElZSxRbOePhizjUL2qe6qLbBQaAwExP+18lljX9wxTGGpHWVXFiqcp7xGVkwmgEONEjMdPNhQvSFNx4KcmbLojIYFimY1UW8zpT+dE/46/52avw7D7ghG8IdFHFi+Ulri/3Ty/Hnhs8ucZm4L7k0GpluZalnhdGAq1LMOXIGzw2Q5xALAq+7Ko2sFmiibMC9jwHXXdvnqvcwN0aLFZ6hSxaDCpzhCQmnNN/f9NM 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 Tue, Nov 11, 2025 at 12:04 AM Tejun Heo wrote: > > Hello, Hi Tejun, > > On Mon, Nov 10, 2025 at 02:50:11PM +0100, Michal Koutnı wrote: > > All in all, I'd like to have more backing data on insufficiency of (all > > the) rstat optimizations before opening explicit flushes like this > > (especially when it's meant to be exposed by BPF already). > > +1. If the current behavior introduces errors too significant to ignore, I'd > much rather see it fixed from the implementation side rather than exposing > internal operation details like this. > I haven't observed any significant errors with the current behavior. That said, I agree that we should focus on improving the flushing implementation to enhance stats accuracy on high-core-count systems. I'll review both the synchronous and asynchronous flushing paths to see where we can tighten things up. Thanks, Leon