From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aubrey Li Subject: [PATCH v16 3/3] Documentation/filesystems/proc.txt: add AVX512_elapsed_ms Date: Wed, 17 Apr 2019 18:18:40 +0800 Message-ID: <20190417101840.2926-3-aubrey.li@linux.intel.com> References: <20190417101840.2926-1-aubrey.li@linux.intel.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20190417101840.2926-1-aubrey.li@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org To: tglx@linutronix.de, mingo@redhat.com, peterz@infradead.org, hpa@zytor.com Cc: ak@linux.intel.com, tim.c.chen@linux.intel.com, dave.hansen@intel.com, arjan@linux.intel.com, adobriyan@gmail.com, akpm@linux-foundation.org, aubrey.li@intel.com, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, Aubrey Li List-Id: linux-api@vger.kernel.org Added AVX512_elapsed_ms in /proc//status. Report it in Documentation/filesystems/proc.txt Signed-off-by: Aubrey Li Cc: Peter Zijlstra Cc: Andi Kleen Cc: Tim Chen Cc: Dave Hansen Cc: Arjan van de Ven Cc: Linux API Cc: Alexey Dobriyan Cc: Andrew Morton --- Documentation/filesystems/proc.txt | 29 ++++++++++++++++++++++++++++- 1 file changed, 28 insertions(+), 1 deletion(-) diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 66cad5c86171..c4a9e48681ad 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -207,6 +207,7 @@ read the file /proc/PID/status: Speculation_Store_Bypass: thread vulnerable voluntary_ctxt_switches: 0 nonvoluntary_ctxt_switches: 1 + AVX512_elapsed_ms: 8 This shows you nearly the same information you would get if you viewed it with the ps command. In fact, ps uses the proc file system to obtain its @@ -224,7 +225,7 @@ asynchronous manner and the value may not be very precise. To see a precise snapshot of a moment, you can see /proc//smaps file and scan page table. It's slow but very precise. -Table 1-2: Contents of the status files (as of 4.19) +Table 1-2: Contents of the status files (as of 5.1) .............................................................................. Field Content Name filename of the executable @@ -289,6 +290,32 @@ Table 1-2: Contents of the status files (as of 4.19) Mems_allowed_list Same as previous, but in "list format" voluntary_ctxt_switches number of voluntary context switches nonvoluntary_ctxt_switches number of non voluntary context switches + AVX512_elapsed_ms time elapsed since last AVX512 usage recorded + + AVX512_elapsed_ms: + ------------------ + If AVX512 is supported on the machine, this entry shows the milliseconds + elapsed since the last time AVX512 usage was recorded. The recording + happens on a best effort basis when a task is scheduled out. This means + that the value depends on two factors: + + 1) The time which the task spent on the CPU without being scheduled + out. With CPU isolation and a single runnable task this can take + several seconds. + + 2) The time since the task was scheduled out last. Depending on the + reason for being scheduled out (time slice exhausted, syscall ...) + this can be arbitrary long time. + + As a consequence the value cannot be considered precise and authoritative + information. The application which uses this information has to be aware + of the overall scenario on the system in order to determine whether a + task is a real AVX512 user or not. + + A special value of '-1' indicates that no AVX512 usage was recorded, thus + the task is unlikely an AVX512 user, but depends on the workload and the + scheduling scenario, it also could be a false negative mentioned above. + .............................................................................. Table 1-3: Contents of the statm files (as of 2.6.8-rc3) -- 2.21.0