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Mon, 9 Jun 2025 08:55:50 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id TC1jEZahRmioEQAAD6G6ig (envelope-from ); Mon, 09 Jun 2025 08:55:50 +0000 Message-ID: <06d9981e-4a4a-4b99-9418-9dec0a3420e8@suse.cz> Date: Mon, 9 Jun 2025 10:56:46 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm: fix the inaccurate memory statistics issue for users From: Vlastimil Babka To: "Ritesh Harjani (IBM)" , Baolin Wang , Michal Hocko Cc: akpm@linux-foundation.org, david@redhat.com, shakeel.butt@linux.dev, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, rppt@kernel.org, surenb@google.com, donettom@linux.ibm.com, aboorvad@linux.ibm.com, sj@kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org References: <87bjqx4h82.fsf@gmail.com> <890b825e-b3b1-4d32-83ec-662495e35023@linux.alibaba.com> <87a56h48ow.fsf@gmail.com> <4c113d58-c858-4ef8-a7f1-bae05c293edf@suse.cz> Content-Language: en-US In-Reply-To: <4c113d58-c858-4ef8-a7f1-bae05c293edf@suse.cz> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspam-User: X-Rspamd-Queue-Id: 2DF94120002 X-Rspamd-Server: rspam09 X-Stat-Signature: ezzm3y3r8u4wtda3j4hrdfukbi3xrq8m X-HE-Tag: 1749459352-932272 X-HE-Meta: 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 jKfJ7yd0 ACAUp9HcfZK/hQV/46LG+nOdkxUqUJqIVUL0e/pnnc26c75plSV4uZfgrzeOLSCqAn+FtvNVBYWo7lYNBi08V44VFKezdWtCeYYvSzQZ+GdQL2m9lpbTMwgR7Zg+6QUwMnVjoVg3IXy4FAXGUTh7iKhzXYFc9gIoPixbTy6NH/WheCsCulHR04Ue+NAQFnhgE2stAnh1R/0lwF794zV3xIp+VQSyPyANwiJv5G8CeJRF7zu5B6/heryNFl77TUEd5g1AWYxQhPDHGBkizFsOWrUSWmu0V41lMxRdH31DDL83Cd17+1F2zlAOc9FsAJVuelc3JtfV6M7oh4BVtbKEUXPica5/NbIlTxxwV6NVENUSyCAYWYza6ZPbTOsLyNjA3IeY7 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 6/9/25 10:52 AM, Vlastimil Babka wrote: > On 6/9/25 10:31 AM, Ritesh Harjani (IBM) wrote: >> Baolin Wang writes: >> >>> On 2025/6/9 15:35, Michal Hocko wrote: >>>> On Mon 09-06-25 10:57:41, Ritesh Harjani wrote: >>>>> >>>>> Any reason why we dropped the Fixes tag? I see there were a series of >>>>> discussion on v1 and it got concluded that the fix was correct, then why >>>>> drop the fixes tag? >>>> >>>> This seems more like an improvement than a bug fix. >>> >>> Yes. I don't have a strong opinion on this, but we (Alibaba) will >>> backport it manually, >>> >>> because some of user-space monitoring tools depend >>> on these statistics. >> >> That sounds like a regression then, isn't it? > > Hm if counters were accurate before f1a7941243c1 and not afterwards, and > this is making them accurate again, and some userspace depends on it, > then Fixes: and stable is probably warranted then. If this was just a > perf improvement, then not. But AFAIU f1a7941243c1 was the perf > improvement... Dang, should have re-read the commit log of f1a7941243c1 first. It seems like the error margin due to batching existed also before f1a7941243c1. " This patch converts the rss_stats into percpu_counter to convert the error margin from (nr_threads * 64) to approximately (nr_cpus ^ 2)." so if on some systems this means worse margin than before, the above "if" chain of thought might still hold. > >> -ritesh >