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AJvYcCVXMahiYQP5bF0dtUM/aI5WKRc6Qyp/nqxzzdq6YkpcqNaOvlEZpxbDkXTdJV03BnglNhZ1gLnwZBF88ncOdUdK0RE= X-Gm-Message-State: AOJu0YzAJKcxSWHpPxh2R9SU90RC8i1x9aNmq7ZdIf/dgB3wNXoyeX+H R7k/MozNsXxV9b7h+6Utnd4ASKVSjCDHzcIHgYyl6oQ/uzjgugJn9CccxrcjvrVHHz/OWLA9XjL izmb4N694gYoOZQqG/2zreCrUWzs2SZdsDpVAMw== X-Google-Smtp-Source: AGHT+IFOo5v2gCv2PX+RdUyGaQBAua2+I57mJ1JpmFBMQL4D5cDPDjygDA0gX9IstRVpbEb/VqTA8cw+o2bGmAR1xJE= X-Received: by 2002:a05:622a:1446:b0:447:d87e:7873 with SMTP id d75a77b69052e-44fa538f761mr162011641cf.64.1721832277575; Wed, 24 Jul 2024 07:44:37 -0700 (PDT) MIME-Version: 1.0 References: <20240718202611.1695164-1-pasha.tatashin@soleen.com> <20240723234600.d05817293ec1eb2d4ad87be7@linux-foundation.org> In-Reply-To: <20240723234600.d05817293ec1eb2d4ad87be7@linux-foundation.org> From: Pasha Tatashin Date: Wed, 24 Jul 2024 10:43:59 -0400 Message-ID: Subject: Re: [PATCH v4] vmstat: Kernel stack usage histogram To: Andrew Morton Cc: jpoimboe@kernel.org, kent.overstreet@linux.dev, peterz@infradead.org, nphamcs@gmail.com, cerasuolodomenico@gmail.com, surenb@google.com, lizhijian@fujitsu.com, willy@infradead.org, shakeel.butt@linux.dev, vbabka@suse.cz, ziy@nvidia.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: C12E0180016 X-Stat-Signature: fa4sg8k8jwhwif8gr7xfi19emfuphj73 X-Rspam-User: X-HE-Tag: 1721832278-467743 X-HE-Meta: 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 pTrSDd8q +IFkgcssZEO53SwAjGMqXC/Uyc4bPSvxiiCa5Fijy2hOGV/BglaFRFM8QgINgagjiY8umutyFDr8A/yvcqVTjX6EOyh1BuSDbkewnptLqEhZ7f7oZ22mfjZpnbYWjPWRLW3AldtILVhUEtkf1ipbgdlZNVVYNCY3Jh5ur/SKjSox45l9yKKoD81hpMYqs5HTsQv3wiI+zRANn5rslTilJeuyuSERpP9TcmM1jFehU+cTdVJ2O7UGkNjTWVnz9HgE3QZkYXVDlRsopo5WyW74P+ZhH8LTZaJV58AsaIMQ9po4iazHj3hO1FwyNtrm2Z7zVgb3hRUzJgdmMbXsaGPVA3XVTcd2SJOgHX2ox X-Bogosity: Ham, tests=bogofilter, spamicity=0.000014, 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, Jul 24, 2024 at 2:46=E2=80=AFAM Andrew Morton wrote: > > On Thu, 18 Jul 2024 20:26:11 +0000 Pasha Tatashin wrote: > > > As part of the dynamic kernel stack project, we need to know the amount > > of data that can be saved by reducing the default kernel stack size [1]= . > > > > Provide a kernel stack usage histogram to aid in optimizing kernel stac= k > > sizes and minimizing memory waste in large-scale environments. The > > histogram divides stack usage into power-of-two buckets and reports the > > results in /proc/vmstat. This information is especially valuable in > > environments with millions of machines, where even small optimizations > > can have a significant impact. > > x86_64 allmodconfig: > > In file included from : > In function 'init_memcg_events', > inlined from 'mem_cgroup_css_alloc' at mm/memcontrol.c:3616:3: > ././include/linux/compiler_types.h:510:45: error: call to '__compiletime_= assert_2305' declared with attribute error: BUILD_BUG_ON failed: NR_VM_EVEN= T_ITEMS >=3D S8_MAX > 510 | _compiletime_assert(condition, msg, __compiletime_assert_= , __COUNTER__) > | ^ > ././include/linux/compiler_types.h:491:25: note: in definition of macro '= __compiletime_assert' > 491 | prefix ## suffix(); = \ > | ^~~~~~ > ././include/linux/compiler_types.h:510:9: note: in expansion of macro '_c= ompiletime_assert' > 510 | _compiletime_assert(condition, msg, __compiletime_assert_= , __COUNTER__) > | ^~~~~~~~~~~~~~~~~~~ > ./include/linux/build_bug.h:39:37: note: in expansion of macro 'compileti= me_assert' > 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), m= sg) > | ^~~~~~~~~~~~~~~~~~ > ./include/linux/build_bug.h:50:9: note: in expansion of macro 'BUILD_BUG_= ON_MSG' > 50 | BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #cond= ition) > | ^~~~~~~~~~~~~~~~ > mm/memcontrol.c:444:9: note: in expansion of macro 'BUILD_BUG_ON' > 444 | BUILD_BUG_ON(NR_VM_EVENT_ITEMS >=3D S8_MAX); > | ^~~~~~~~~~~~ > > This looks legitimate - is it time to switch to int16_t? I am looking into this, and will also uninline stack_not_used() and kstack_histogram() as discussed earlier in the thread. Pasha