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Tue, 27 Feb 2024 09:30:21 +0000 (UTC) Received: from dovecot-director2.suse.de ([10.150.64.162]) by imap1.dmz-prg2.suse.org with ESMTPSA id QuGyKq2r3WW8cgAAD6G6ig (envelope-from ); Tue, 27 Feb 2024 09:30:21 +0000 Message-ID: <72cc5f0b-90cc-48a8-a026-412fa1186acd@suse.cz> Date: Tue, 27 Feb 2024 10:30:53 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 15/36] lib: introduce support for page allocation tagging Content-Language: en-US To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, kent.overstreet@linux.dev, mhocko@suse.com, hannes@cmpxchg.org, roman.gushchin@linux.dev, mgorman@suse.de, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, penguin-kernel@i-love.sakura.ne.jp, corbet@lwn.net, void@manifault.com, peterz@infradead.org, juri.lelli@redhat.com, catalin.marinas@arm.com, will@kernel.org, arnd@arndb.de, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, x86@kernel.org, peterx@redhat.com, david@redhat.com, axboe@kernel.dk, mcgrof@kernel.org, masahiroy@kernel.org, nathan@kernel.org, dennis@kernel.org, tj@kernel.org, muchun.song@linux.dev, rppt@kernel.org, paulmck@kernel.org, pasha.tatashin@soleen.com, yosryahmed@google.com, yuzhao@google.com, dhowells@redhat.com, hughd@google.com, andreyknvl@gmail.com, keescook@chromium.org, ndesaulniers@google.com, vvvvvv@google.com, gregkh@linuxfoundation.org, ebiggers@google.com, ytcoode@gmail.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, bristot@redhat.com, vschneid@redhat.com, cl@linux.com, penberg@kernel.org, iamjoonsoo.kim@lge.com, 42.hyeyoo@gmail.com, glider@google.com, elver@google.com, dvyukov@google.com, shakeelb@google.com, songmuchun@bytedance.com, jbaron@akamai.com, rientjes@google.com, minchan@google.com, kaleshsingh@google.com, kernel-team@android.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux.dev, linux-arch@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-modules@vger.kernel.org, kasan-dev@googlegroups.com, cgroups@vger.kernel.org References: <20240221194052.927623-1-surenb@google.com> <20240221194052.927623-16-surenb@google.com> From: Vlastimil Babka In-Reply-To: Content-Type: text/plain; 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RCVD_TLS_ALL(0.00)[]; SUSPICIOUS_RECIPS(1.50)[] X-Spam-Level: * X-Spam-Score: 1.39 X-Spam-Flag: NO On 2/26/24 18:11, Suren Baghdasaryan wrote: > On Mon, Feb 26, 2024 at 9:07 AM Vlastimil Babka wrote: >> >> On 2/21/24 20:40, Suren Baghdasaryan wrote: >>> Introduce helper functions to easily instrument page allocators by >>> storing a pointer to the allocation tag associated with the code that >>> allocated the page in a page_ext field. >>> >>> Signed-off-by: Suren Baghdasaryan >>> Co-developed-by: Kent Overstreet >>> Signed-off-by: Kent Overstreet >> >> The static key usage seems fine now. Even if the page_ext overhead is still >> always paid when compiled in, you mention in the cover letter there's a plan >> for boot-time toggle later, so > > Yes, I already have a simple patch for that to be included in the next > revision: https://github.com/torvalds/linux/commit/7ca367e80232345f471b77b3ea71cf82faf50954 This opt-out logic would require a distro kernel with allocation profiling compiled-in to ship together with something that modifies kernel command line to disable it by default, so it's not very practical. Could the CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT be turned into having 3 possible choices, where one of them would initialize mem_profiling_enabled to false? Or, taking a step back, is it going to be a common usecase to pay the memory overhead unconditionally, but only enable the profiling later during runtime? Also what happens if someone would enable and disable it multiple times during one boot? Would the statistics get all skewed because some frees would be not accounted while it's disabled? >> >> Reviewed-by: Vlastimil Babka > > Thanks! > >> >>