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From: Kent Overstreet To: Vlastimil Babka Cc: Suren Baghdasaryan , akpm@linux-foundation.org, 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 Subject: Re: [PATCH v4 15/36] lib: introduce support for page allocation tagging Message-ID: References: <20240221194052.927623-1-surenb@google.com> <20240221194052.927623-16-surenb@google.com> <72cc5f0b-90cc-48a8-a026-412fa1186acd@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <72cc5f0b-90cc-48a8-a026-412fa1186acd@suse.cz> X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: AA989140003 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: g3sq8a6b1giddmxz7f7tcmd71517ookd X-HE-Tag: 1709027166-865012 X-HE-Meta: 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 JzA9OZx9 H0KiAI/89KoR5n3LSUhX3uyqQZoaUeoIiXSnui85UcbMs2zqgezNdJPyWGT77fLvYhXmjnFHIFFBI9O9o7aFcNJNLSDY7MeS0VkY+Z8vNC7tC61EG7BwNvJMs4x4FWXvpD6Inh6bg8uiDdLvysv249Z2SUdn+WoVCwTifLsU7I6j9P23vAYHEcLfmm89qEg30rTLMRU68hHHfJTSkyP1PdFQUu/vLK8fYJDqiLuA4iravrvY= 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, Feb 27, 2024 at 10:30:53AM +0100, Vlastimil Babka wrote: > > > 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? I already wrote the code for fast lookup from codetag index -> codetag - i.e. pointer compression - so this is all going away shortly. It just won't be in the initial pull request because of other dependencies (it requires my eytzinger code, which I was already lifting from fs/bcachefs/ for 6.9), but it can still probably make 6.9 in a second smaller pull.