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Docs/admin-guide/mm/damon/stat: document negative idle time

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Commit a983a26d52 ("mm/damon/stat: expose negative idle time")
introduced the negative idle time feature for DAMON_STAT.  But it is not
documented.  Document it on the usage document.

Link: https://lkml.kernel.org/r/20251026182216.118200-9-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
SeongJae Park
2025-10-26 11:22:13 -07:00
committed by Andrew Morton
parent da8644a476
commit f46dbea0d9
1 changed files with 8 additions and 7 deletions
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15
Documentation/admin-guide/mm/damon/stat.rst
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@@ -74,12 +74,13 @@ memory_idle_ms_percentiles
Per-byte idle time (milliseconds) percentiles of the system.
DAMON_STAT calculates how long each byte of the memory was not accessed until
now (idle time), based on the current DAMON results snapshot. If DAMON found a
region of access frequency (nr_accesses) larger than zero, every byte of the
region gets zero idle time. If a region has zero access frequency
(nr_accesses), how long the region was keeping the zero access frequency (age)
becomes the idle time of every byte of the region. Then, DAMON_STAT exposes
the percentiles of the idle time values via this read-only parameter. Reading
the parameter returns 101 idle time values in milliseconds, separated by comma.
now (idle time), based on the current DAMON results snapshot. For regions
having access frequency (nr_accesses) larger than zero, how long the current
access frequency level was kept multiplied by ``-1`` becomes the idlee time of
every byte of the region. If a region has zero access frequency (nr_accesses),
how long the region was keeping the zero access frequency (age) becomes the
idle time of every byte of the region. Then, DAMON_STAT exposes the
percentiles of the idle time values via this read-only parameter. Reading the
parameter returns 101 idle time values in milliseconds, separated by comma.
Each value represents 0-th, 1st, 2nd, 3rd, ..., 99th and 100th percentile idle
times.