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Sat, 24 May 2025 09:29:18 +0800 Message-ID: <99e39ac1-d766-4d6e-a69a-525c49662ac0@linux.alibaba.com> Date: Sat, 24 May 2025 09:29:16 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH] mm: fix the inaccurate memory statistics issue for users To: SeongJae Park Cc: akpm@linux-foundation.org, david@redhat.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, shakeel.butt@linux.dev References: <20250523172305.57843-1-sj@kernel.org> From: Baolin Wang In-Reply-To: <20250523172305.57843-1-sj@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 17A9D40005 X-Stat-Signature: o5ncigjauaj5yg5rxi94yw1bfyguxmu5 X-Rspam-User: X-HE-Tag: 1748050162-307984 X-HE-Meta: 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 qxSwJCey O5QZx0DAW3FYmrfgx8zlDahgNrLBJVqUXGYSKgYec/tYnVlbgoHNKoPXF2euZRKg0SRpGNlAsgMLr4XVcY+viv5n6xFd+cLfj+/ccLrsb2aOSdd69WUAqggS6o7AqSwYtteOrYUIOfUZtklmODX0XLIR2uhgnnJJ9cM2xjFy1IRzbuH9B3mMq85LkODkgWtrDmaxO9S7wRKfg2bpmOObjmFsvppVT1z/L9Wb2unzRg5/+L5GeASar2VBjIbG2vfoG0dY2LDLKHcNApW09S/EjrtJkZBHVzafRKClvtxA4lySyZ3xx0UoAKBf1LZ868DwJbPwiKgW+HlLNuYYPP8C9aDeHMA== 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 2025/5/24 01:23, SeongJae Park wrote: > On Fri, 23 May 2025 10:20:29 -0700 SeongJae Park wrote: > >> On Fri, 23 May 2025 11:16:13 +0800 Baolin Wang wrote: >> >>> On some large machines with a high number of CPUs running a 64K kernel, >> >> What does 64K kernel means? Sorry for not being clear. I mean a 64K pagesize kernel on Arm servers. >>> we found that the 'RES' field is always 0 displayed by the top command >>> for some processes, which will cause a lot of confusion for users. >>> >>> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND >>> 875525 root 20 0 12480 0 0 R 0.3 0.0 0:00.08 top >>> 1 root 20 0 172800 0 0 S 0.0 0.0 0:04.52 systemd >>> >>> The main reason is that the batch size of the percpu counter is quite large >>> on these machines, caching a significant percpu value, since converting mm's >>> rss stats into percpu_counter by commit f1a7941243c1 ("mm: convert mm's rss >>> stats into percpu_counter"). > > Forgot asking this, sorry. Should we add Fixes: tag and Cc stable@? Yes, will add the Fixes tag in next version. Thanks for reviewing.