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From: Shakeel Butt To: JP Kobryn Cc: andrii@kernel.org, ast@kernel.org, mkoutny@suse.com, yosryahmed@google.com, hannes@cmpxchg.org, tj@kernel.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, bpf@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH v2 1/2] memcg: introduce kfuncs for fetching memcg stats Message-ID: References: <20251015190813.80163-1-inwardvessel@gmail.com> <20251015190813.80163-2-inwardvessel@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251015190813.80163-2-inwardvessel@gmail.com> X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam01 X-Stat-Signature: z437i1rsfp9n4djhrocou3ruko7kdnnr X-Rspam-User: X-Rspamd-Queue-Id: 9B67D40007 X-HE-Tag: 1760561313-257821 X-HE-Meta: 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 zTjiztBi 7K8eWYowKd2IhSlgBpTyeeoXzl6+ejp51Aj8lBS8QarIf93bcYmtrS/n46DaqhkDWhqSFpY+j2WEix0biHP3DuFtj+XfkZVNeVjlfwvRlCe1bujhcNzj91wvPDDeTAbSwmGT4YMU+qm7a3+SpD0Xp8FXyufM8jOsKq0tGf/d/FDtLHkVC7h4EjwfNJl9HbZxqC8wUFlZFbpZoNPP/8VlLhIhgwSUXPnS5W9QpnDdDNKL9IAA= 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 Wed, Oct 15, 2025 at 12:08:12PM -0700, JP Kobryn wrote: > Reading from the memory.stat file can be expensive because of the string > encoding/decoding and text filtering involved. Introduce three kfuncs for > fetching each type of memcg stat from a bpf program. This allows data to be > transferred directly to userspace, eliminating the need for string > encoding/decoding. It also removes the need for text filtering since it > allows for fetching specific stats. > > The patch also includes a kfunc for flushing stats in order to read the > latest values. Note that this is not required for fetching stats, since the > kernel periodically flushes memcg stats. It is left up to the programmer > whether they want more recent stats or not. > > Signed-off-by: JP Kobryn Acked-by: Shakeel Butt