linux.git/Documentation/trace/postprocess, branch v6.6.132

docs: ftrace: always use canonical ftrace path

2023-01-31T21:02:30+00:00

The canonical location for the tracefs filesystem is at /sys/kernel/tracing.

But, from Documentation/trace/ftrace.rst:

  Before 4.1, all ftrace tracing control files were within the debugfs
  file system, which is typically located at /sys/kernel/debug/tracing.
  For backward compatibility, when mounting the debugfs file system,
  the tracefs file system will be automatically mounted at:

  /sys/kernel/debug/tracing

Many parts of Documentation still reference this older debugfs path, so
let's update them to avoid confusion.

Signed-off-by: Ross Zwisler 
Reviewed-by: Steven Rostedt (Google) 
Link: https://lore.kernel.org/r/20230125213251.2013791-1-zwisler@google.com
Signed-off-by: Jonathan Corbet

tweewide: Fix most Shebang lines

2020-12-08T14:30:04+00:00

Change every shebang which does not need an argument to use /usr/bin/env.
This is needed as not every distro has everything under /usr/bin,
sometimes not even bash.

Signed-off-by: Finn Behrens 
Signed-off-by: Masahiro Yamada

mm: move recent_rotated pages calculation to shrink_inactive_list()

2019-05-14T16:47:45+00:00

Patch series "mm: Generalize putback functions"]

putback_inactive_pages() and move_active_pages_to_lru() are almost
similar, so this patchset merges them ina single function.

This patch (of 4):

The patch moves the calculation from putback_inactive_pages() to
shrink_inactive_list().  This makes putback_inactive_pages() looking more
similar to move_active_pages_to_lru().

To do that, we account activated pages in reclaim_stat::nr_activate.
Since a page may change its LRU type from anon to file cache inside
shrink_page_list() (see ClearPageSwapBacked()), we have to account pages
for the both types.  So, nr_activate becomes an array.

Previously we used nr_activate to account PGACTIVATE events, but now we
account them into pgactivate variable (since they are about number of
pages in general, not about sum of hpage_nr_pages).

Link: http://lkml.kernel.org/r/155290127956.31489.3393586616054413298.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai 
Reviewed-by: Daniel Jordan 
Cc: Michal Hocko 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, page_alloc: wakeup kcompactd even if kswapd cannot free more memory

2018-04-06T04:36:27+00:00

Kswapd will not wakeup if per-zone watermarks are not failing or if too
many previous attempts at background reclaim have failed.

This can be true if there is a lot of free memory available.  For high-
order allocations, kswapd is responsible for waking up kcompactd for
background compaction.  If the zone is not below its watermarks or
reclaim has recently failed (lots of free memory, nothing left to
reclaim), kcompactd does not get woken up.

When __GFP_DIRECT_RECLAIM is not allowed, allow kcompactd to still be
woken up even if kswapd will not reclaim.  This allows high-order
allocations, such as thp, to still trigger background compaction even
when the zone has an abundance of free memory.

Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1803111659420.209721@chino.kir.corp.google.com
Signed-off-by: David Rientjes 
Acked-by: Vlastimil Babka 
Cc: Mel Gorman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

trace-vmscan-postprocess: sync with tracepoints updates

2017-02-23T00:41:29+00:00

Both mm_vmscan_lru_shrink_active and mm_vmscan_lru_isolate have changed
so the script needs to be update to reflect those changes

Link: http://lkml.kernel.org/r/20170105151737.GU21618@dhcp22.suse.cz
Signed-off-by: Michal Hocko 
Acked-by: Hillf Danton 
Acked-by: Mel Gorman 
Acked-by: Vlastimil Babka 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

x86, tracing, perf: Add trace point for MSR accesses

2015-12-06T11:56:10+00:00

For debugging low level code interacting with the CPU it is often
useful to trace the MSR read/writes. This gives a concise summary of
PMU and other operations.

perf has an ad-hoc way to do this using trace_printk, but it's
somewhat limited (and also now spews ugly boot messages when enabled)

Instead define real trace points for all MSR accesses.

This adds three new trace points: read_msr and write_msr and rdpmc.

They also report if the access faulted (if *_safe is used)

This allows filtering and triggering on specific MSR values, which
allows various more advanced debugging techniques.

All the values are well defined in the CPU documentation.

The trace can be post processed with
Documentation/trace/postprocess/decode_msr.py to add symbolic MSR
names to the trace.

I only added it to native MSR accesses in C, not paravirtualized or in
entry*.S (which is not too interesting)

Originally the patch kit moved the MSRs out of line.  This uses an
alternative approach recommended by Steven Rostedt of only moving the
trace calls out of line, but open coding the access to the jump label.

Signed-off-by: Andi Kleen 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Steven Rostedt 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Link: http://lkml.kernel.org/r/1449018060-1742-3-git-send-email-andi@firstfloor.org
Signed-off-by: Ingo Molnar

mm: trace-vmscan-postprocess.pl: report the number of file/anon pages respectively

2014-08-07T01:01:20+00:00

Until now, the reporting from trace-vmscan-postprocess.pl is not very
useful because we cannot directly use this script for checking the
file/anon ratio of scanning.  This patch aims to report respectively the
number of file/anon pages which were scanned/reclaimed by kswapd or
direct-reclaim.  Sample output is usually something like the following.

Summary
Direct reclaims:                          8823
Direct reclaim pages scanned:             2438797
Direct reclaim file pages scanned:        1315200
Direct reclaim anon pages scanned:        1123597
Direct reclaim pages reclaimed:           446139
Direct reclaim file pages reclaimed:      378668
Direct reclaim anon pages reclaimed:      67471
Direct reclaim write file sync I/O:       0
Direct reclaim write anon sync I/O:       0
Direct reclaim write file async I/O:      0
Direct reclaim write anon async I/O:      4240
Wake kswapd requests:                     122310
Time stalled direct reclaim:              13.78 seconds

Kswapd wakeups:                           25817
Kswapd pages scanned:                     170779115
Kswapd file pages scanned:                162725123
Kswapd anon pages scanned:                8053992
Kswapd pages reclaimed:                   129065738
Kswapd file pages reclaimed:              128500930
Kswapd anon pages reclaimed:              564808
Kswapd reclaim write file sync I/O:       0
Kswapd reclaim write anon sync I/O:       0
Kswapd reclaim write file async I/O:      36
Kswapd reclaim write anon async I/O:      730730
Time kswapd awake:                        1015.50 seconds

Signed-off-by: Chen Yucong 
Cc: Mel Gorman 
Cc: Johannes Weiner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm:vmscan: update the trace-vmscan-postprocess.pl for event vmscan/mm_vmscan_lru_isolate

2014-07-03T16:21:54+00:00

When using trace-vmscan-postprocess.pl for checking the file/anon rate
of scanning, we can find that it can not be performed.  At the same
time, the following message will be reported:

  WARNING: Format not as expected for event vmscan/mm_vmscan_lru_isolate
  'file' != 'contig_taken' Fewer fields than expected in format at
  ./trace-vmscan-postprocess.pl line 171,  line 76.

In trace-vmscan-postprocess.pl, (contig_taken, contig_dirty, and
contig_failed) are be associated respectively to (nr_lumpy_taken,
nr_lumpy_dirty, and nr_lumpy_failed) for lumpy reclaim.  Via commit
c53919adc045 ("mm: vmscan: remove lumpy reclaim"), lumpy reclaim had
already been removed by Mel, but the update for
trace-vmscan-postprocess.pl was missed.

Signed-off-by: Chen Yucong 
Cc: Mel Gorman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Documentation/trace/postprocess/trace-vmscan-postprocess.pl: fix the traceevent regex

2014-01-24T00:36:52+00:00

When irq, preempt and lockdep fields are printed (field 3 in the example
below) in the trace output, the script fails.

An example entry:
  kswapd0-610   [000] ...1   158.112152: mm_vmscan_kswapd_wake: nid=0 order=0

Signed-off-by: Vinayak Menon 
Cc: Mel Gorman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm-tracepoint: rename page-free events

2012-01-11T00:30:41+00:00

Rename mm_page_free_direct into mm_page_free and mm_pagevec_free into
mm_page_free_batched

Since v2.6.33-5426-gc475dab the kernel triggers mm_page_free_direct for
all freed pages, not only for directly freed.  So, let's name it properly.
 For pages freed via page-list we also trigger mm_page_free_batched event.

Signed-off-by: Konstantin Khlebnikov 
Cc: Mel Gorman 
Cc: KOSAKI Motohiro 
Reviewed-by: Minchan Kim 
Cc: Hugh Dickins 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds