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psi: clarify the units used in pressure files

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The output of the PSI files show a bunch of numbers with no unit.  The
psi.txt documentation file also does not indicate what units are used.
One can only find out by looking at the source code.  The units are
percentage for the averages and useconds for the total.  Make the
information easier to find by documenting the units in psi.txt.

Link: http://lkml.kernel.org/r/20190402193810.3450-1-longman@redhat.com
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Waiman Long 2019-04-05 18:39:14 -07:00 committed by Linus Torvalds
parent c6f3c5ee40
commit be87ab0afd
1 changed files with 6 additions and 6 deletions
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12
Documentation/accounting/psi.txt
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@ -56,12 +56,12 @@ situation from a state where some tasks are stalled but the CPU is
still doing productive work. As such, time spent in this subset of the
stall state is tracked separately and exported in the "full" averages.
The ratios are tracked as recent trends over ten, sixty, and three
hundred second windows, which gives insight into short term events as
well as medium and long term trends. The total absolute stall time is
tracked and exported as well, to allow detection of latency spikes
which wouldn't necessarily make a dent in the time averages, or to
average trends over custom time frames.
The ratios (in %) are tracked as recent trends over ten, sixty, and
three hundred second windows, which gives insight into short term events
as well as medium and long term trends. The total absolute stall time
(in us) is tracked and exported as well, to allow detection of latency
spikes which wouldn't necessarily make a dent in the time averages,
or to average trends over custom time frames.
Cgroup2 interface
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