From: Aubrey Li <aubrey.li@linux.intel.com>
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 <aubrey.li@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>
Subject: [PATCH v18 3/3] Documentation/filesystems/proc.txt: add arch_status file
Date: Thu, 25 Apr 2019 22:32:19 +0800 [thread overview]
Message-ID: <20190425143219.102258-3-aubrey.li@linux.intel.com> (raw)
In-Reply-To: <20190425143219.102258-1-aubrey.li@linux.intel.com>
Added /proc/<pid>/arch_status file, and added AVX512_elapsed_ms in
/proc/<pid>/arch_status. Report it in Documentation/filesystems/proc.txt
Signed-off-by: Aubrey Li <aubrey.li@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linux API <linux-api@vger.kernel.org>
---
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/<pid>/map_files - Information about memory mapped files
3.10 /proc/<pid>/timerslack_ns - Task timerslack value
3.11 /proc/<pid>/patch_state - Livepatch patch operation state
+ 3.12 /proc/<pid>/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/<pid>/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
next prev parent reply other threads:[~2019-04-25 14:33 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-25 14:32 [PATCH v18 1/3] proc: add /proc/<pid>/arch_status Aubrey Li
2019-04-25 14:32 ` [PATCH v18 2/3] x86,/proc/pid/arch_status: Add AVX-512 usage elapsed time Aubrey Li
2019-04-25 14:32 ` Aubrey Li [this message]
2019-05-24 3:18 ` [PATCH v18 1/3] proc: add /proc/<pid>/arch_status Andrew Morton
2019-05-27 7:16 ` Li, Aubrey
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