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| author | Daniel Bristot de Oliveira <bristot@redhat.com> | 2021-06-22 16:42:20 +0200 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2021-06-24 15:37:56 -0400 |
| commit | 8fa826b7344d6752f5cfd72380d9fe7bd8c6b928 (patch) | |
| tree | cf816b11e48b2ee54742dcdadfade999d56f3cfe /Documentation/trace | |
| parent | bb1b24cf41b5b3b96a921f80f9799e7be75f167d (diff) | |
| download | linux-8fa826b7344d6752f5cfd72380d9fe7bd8c6b928.tar.gz | |
trace/hwlat: Implement the mode config option
Provides the "mode" config to the hardware latency detector. hwlatd has
two different operation modes. The default mode is the "round-robin" one,
in which a single hwlatd thread runs, migrating among the allowed CPUs in a
"round-robin" fashion. This is the current behavior.
The "none" sets the allowed cpumask for a single hwlatd thread at the
startup, but skips the round-robin, letting the scheduler handle the
migration.
In preparation to the per-cpu mode.
Link: https://lkml.kernel.org/r/f3b1271262aa030c680e26615c1b9b2d71e55e92.1624372313.git.bristot@redhat.com
Cc: Phil Auld <pauld@redhat.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Kate Carcia <kcarcia@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Alexandre Chartre <alexandre.chartre@oracle.com>
Cc: Clark Willaims <williams@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'Documentation/trace')
| -rw-r--r-- | Documentation/trace/hwlat_detector.rst | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/Documentation/trace/hwlat_detector.rst b/Documentation/trace/hwlat_detector.rst index 5739349649c882..4d952df0586a60 100644 --- a/Documentation/trace/hwlat_detector.rst +++ b/Documentation/trace/hwlat_detector.rst @@ -76,8 +76,12 @@ in /sys/kernel/tracing: - tracing_cpumask - the CPUs to move the hwlat thread across - hwlat_detector/width - specified amount of time to spin within window (usecs) - hwlat_detector/window - amount of time between (width) runs (usecs) + - hwlat_detector/mode - the thread mode -The hwlat detector's kernel thread will migrate across each CPU specified in -tracing_cpumask between each window. To limit the migration, either modify -tracing_cpumask, or modify the hwlat kernel thread (named [hwlatd]) CPU -affinity directly, and the migration will stop. +By default, the hwlat detector's kernel thread will migrate across each CPU +specified in cpumask at the beginning of a new window, in a round-robin +fashion. This behavior can be changed by changing the thread mode, +the available options are: + + - none: do not force migration + - round-robin: migrate across each CPU specified in cpumask [default] |