From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aubrey Li Subject: [PATCH v18 3/3] Documentation/filesystems/proc.txt: add arch_status file Date: Thu, 25 Apr 2019 22:32:19 +0800 Message-ID: <20190425143219.102258-3-aubrey.li@linux.intel.com> References: <20190425143219.102258-1-aubrey.li@linux.intel.com> Return-path: In-Reply-To: <20190425143219.102258-1-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 , Andy Lutomirski List-Id: linux-api@vger.kernel.org Added /proc//arch_status file, and added AVX512_elapsed_ms in /proc//arch_status. Report it in Documentation/filesystems/proc.txt Signed-off-by: Aubrey Li Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: Andi Kleen Cc: Tim Chen Cc: Dave Hansen Cc: Arjan van de Ven Cc: Alexey Dobriyan Cc: Andrew Morton Cc: Andy Lutomirski Cc: Linux API --- Documentation/filesystems/proc.txt | 39 ++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 66cad5c86171..e8bc403d15df 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -45,6 +45,7 @@ Table of Contents 3.9 /proc//map_files - Information about memory mapped files 3.10 /proc//timerslack_ns - Task timerslack value 3.11 /proc//patch_state - Livepatch patch operation state + 3.12 /proc//arch_status - Task architecture specific information 4 Configuring procfs 4.1 Mount options @@ -1948,6 +1949,44 @@ patched. If the patch is being enabled, then the task has already been patched. If the patch is being disabled, then the task hasn't been unpatched yet. +3.12 /proc//arch_status - task architecture specific status +------------------------------------------------------------------- +When CONFIG_PROC_PID_ARCH_STATUS is enabled, this file displays the +architecture specific status of the task. + +Example +------- + $ cat /proc/6753/arch_status + AVX512_elapsed_ms: 8 + +Description +----------- + +x86 specific entries: +--------------------- + 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. ------------------------------------------------------------------------------ Configuring procfs -- 2.17.1