From: Feng Tang <feng.tang@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>,
Arjan van de Ven <arjan@linux.intel.com>,
Jonathan Corbet <corbet@lwn.net>, Ingo Molnar <mingo@kernel.org>,
Eric W Biederman <ebiederm@xmission.com>,
Peter Zijlstra <peterz@infradead.org>,
Dmitry Vyukov <dvyukov@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Andy Lutomirski <luto@kernel.org>,
Ying Huang <ying.huang@intel.com>,
linux-kernel@vger.kernel.org
Cc: Feng Tang <feng.tang@intel.com>
Subject: [RFC PATCH 1/3] kernel/sysctl: add description for "latencytop"
Date: Mon, 29 Apr 2019 16:03:29 +0800 [thread overview]
Message-ID: <1556525011-28022-2-git-send-email-feng.tang@intel.com> (raw)
In-Reply-To: <1556525011-28022-1-git-send-email-feng.tang@intel.com>
The body of description is mostly copied from comments in
kernel/latencytop.c
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Feng Tang <feng.tang@intel.com>
---
Documentation/sysctl/kernel.txt | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index c0527d8..080ef66 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -43,6 +43,7 @@ show up in /proc/sys/kernel:
- hyperv_record_panic_msg
- kexec_load_disabled
- kptr_restrict
+- latencytop
- l2cr [ PPC only ]
- modprobe ==> Documentation/debugging-modules.txt
- modules_disabled
@@ -437,6 +438,23 @@ When kptr_restrict is set to (2), kernel pointers printed using
==============================================================
+latencytop:
+
+This value controls whether to start collecting kernel latency
+data, it is off (0) by default, and could be switched on (1).
+The latency talked here is not the 'traditional' interrupt
+latency (which is primarily caused by something else consuming CPU),
+but instead, it is the latency an application encounters because
+the kernel sleeps on its behalf for various reasons.
+
+The info is exported via /proc/latency_stats and /proc/<pid>/latency.
+
+This file shows up only if CONFIG_LATENCYTOP is enabled, and please
+be noted that turning it on may bring notable sytstem overhead when
+there are massive scheduling in system.
+
+==============================================================
+
l2cr: (PPC only)
This flag controls the L2 cache of G3 processor boards. If
--
2.7.4
next prev parent reply other threads:[~2019-04-29 8:03 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-29 8:03 [RFC PATCH 0/3] latencytop lock usage improvement Feng Tang
2019-04-29 8:03 ` Feng Tang [this message]
2019-04-29 8:03 ` [RFC PATCH 2/3] latencytop: split latency_lock to global lock and per task lock Feng Tang
2019-04-29 8:03 ` [RFC PATCH 3/3] latencytop: add a lazy mode for updating global latency data Feng Tang
2019-04-30 8:09 ` [RFC PATCH 0/3] latencytop lock usage improvement Peter Zijlstra
2019-04-30 8:35 ` Feng Tang
2019-04-30 9:10 ` Peter Zijlstra
2019-04-30 9:22 ` Feng Tang
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