<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/tools/perf/Makefile.perf, branch linux-5.14.y</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>perf trace: Fix the perf trace link location</title>
<updated>2021-07-07T13:28:10+00:00</updated>
<author>
<name>Justin M. Forbes</name>
<email>jforbes@fedoraproject.org</email>
</author>
<published>2021-07-06T18:59:51+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=e63cbfa3bedb4495029a91b924bf910867416aa2'/>
<id>e63cbfa3bedb4495029a91b924bf910867416aa2</id>
<content type='text'>
The install perf_dlfilter.h patch included what seems to be a typo in
the Makefile.perf, which changed the location of the trace link from
'$(DESTDIR_SQ)$(bindir_SQ)/trace' to '$(DESTDIR_SQ)$(dir_SQ)/trace'.

This reverts it back to the correct location.

Fixes: 0beb218315e06e88 ("perf build: Install perf_dlfilter.h")
Signed-off-by: Justin M. Forbes &lt;jforbes@fedoraproject.org&gt;
Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Justin M. Forbes &lt;jmforbes@linuxtx.org&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Link: http://lore.kernel.org/lkml/20210706185952.116121-1-jforbes@fedoraproject.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The install perf_dlfilter.h patch included what seems to be a typo in
the Makefile.perf, which changed the location of the trace link from
'$(DESTDIR_SQ)$(bindir_SQ)/trace' to '$(DESTDIR_SQ)$(dir_SQ)/trace'.

This reverts it back to the correct location.

Fixes: 0beb218315e06e88 ("perf build: Install perf_dlfilter.h")
Signed-off-by: Justin M. Forbes &lt;jforbes@fedoraproject.org&gt;
Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Justin M. Forbes &lt;jmforbes@linuxtx.org&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Link: http://lore.kernel.org/lkml/20210706185952.116121-1-jforbes@fedoraproject.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf stat: Enable BPF counter with --for-each-cgroup</title>
<updated>2021-07-05T17:16:57+00:00</updated>
<author>
<name>Namhyung Kim</name>
<email>namhyung@kernel.org</email>
</author>
<published>2021-07-01T21:12:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=944138f048f7d7591ec7568c94b21de8df2724d4'/>
<id>944138f048f7d7591ec7568c94b21de8df2724d4</id>
<content type='text'>
Recently bperf was added to use BPF to count perf events for various
purposes.  This is an extension for the approach and targetting to
cgroup usages.

Unlike the other bperf, it doesn't share the events with other
processes but it'd reduce unnecessary events (and the overhead of
multiplexing) for each monitored cgroup within the perf session.

When --for-each-cgroup is used with --bpf-counters, it will open
cgroup-switches event per cpu internally and attach the new BPF
program to read given perf_events and to aggregate the results for
cgroups.  It's only called when task is switched to a task in a
different cgroup.

Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
Acked-by: Song Liu &lt;songliubraving@fb.com&gt;
Cc: Andi Kleen &lt;ak@linux.intel.com&gt;
Cc: Ian Rogers &lt;irogers@google.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Stephane Eranian &lt;eranian@google.com&gt;
Link: http://lore.kernel.org/lkml/20210701211227.1403788-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Recently bperf was added to use BPF to count perf events for various
purposes.  This is an extension for the approach and targetting to
cgroup usages.

Unlike the other bperf, it doesn't share the events with other
processes but it'd reduce unnecessary events (and the overhead of
multiplexing) for each monitored cgroup within the perf session.

When --for-each-cgroup is used with --bpf-counters, it will open
cgroup-switches event per cpu internally and attach the new BPF
program to read given perf_events and to aggregate the results for
cgroups.  It's only called when task is switched to a task in a
different cgroup.

Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
Acked-by: Song Liu &lt;songliubraving@fb.com&gt;
Cc: Andi Kleen &lt;ak@linux.intel.com&gt;
Cc: Ian Rogers &lt;irogers@google.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Stephane Eranian &lt;eranian@google.com&gt;
Link: http://lore.kernel.org/lkml/20210701211227.1403788-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf build: Install perf_dlfilter.h</title>
<updated>2021-07-01T19:14:38+00:00</updated>
<author>
<name>Adrian Hunter</name>
<email>adrian.hunter@intel.com</email>
</author>
<published>2021-06-27T13:18:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=0beb218315e06e888acb576909513087e5d1fa5b'/>
<id>0beb218315e06e888acb576909513087e5d1fa5b</id>
<content type='text'>
Users of the --dlfilter option need to include perf_dlfilter.h
in their filters. Install it to the include path.

Signed-off-by: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Andi Kleen &lt;ak@linux.intel.com&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Kan Liang &lt;kan.liang@linux.intel.com&gt;
Cc: Leo Yan &lt;leo.yan@linaro.org&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Link: https://lore.kernel.org/r/20210627131818.810-6-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Users of the --dlfilter option need to include perf_dlfilter.h
in their filters. Install it to the include path.

Signed-off-by: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Andi Kleen &lt;ak@linux.intel.com&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Kan Liang &lt;kan.liang@linux.intel.com&gt;
Cc: Leo Yan &lt;leo.yan@linaro.org&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Link: https://lore.kernel.org/r/20210627131818.810-6-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf tools: Enable libtraceevent dynamic linking</title>
<updated>2021-04-29T13:31:00+00:00</updated>
<author>
<name>Michael Petlan</name>
<email>mpetlan@redhat.com</email>
</author>
<published>2021-04-28T09:20:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=56d32d4cac645bac05fa70d935fa5040e3ab6bb3'/>
<id>56d32d4cac645bac05fa70d935fa5040e3ab6bb3</id>
<content type='text'>
Currently we support only static linking with kernel's libtraceevent
(tools/lib/traceevent). This patch adds libtraceevent package detection
and support to link perf with it dynamically.

  The libtraceevent package status is displayed with:
  $ make VF=1 LIBTRACEEVENT_DYNAMIC=1
  ...
  ...                 libtraceevent: [ on  ]

Default behavior remains the same (static linking).

Committer testing:

  $ make LIBTRACEEVENT_DYNAMIC=1 VF=1 O=/tmp/build/perf -C tools/perf install-bin |&amp; grep traceevent
  Makefile.config:1090: *** Error: No libtraceevent devel library found, please install libtraceevent-devel.  Stop.
  $

Signed-off-by: Michael Petlan &lt;mpetlan@redhat.com&gt;
Tested-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
LPU-Reference: 20210428092023.4009-1-mpetlan@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Currently we support only static linking with kernel's libtraceevent
(tools/lib/traceevent). This patch adds libtraceevent package detection
and support to link perf with it dynamically.

  The libtraceevent package status is displayed with:
  $ make VF=1 LIBTRACEEVENT_DYNAMIC=1
  ...
  ...                 libtraceevent: [ on  ]

Default behavior remains the same (static linking).

Committer testing:

  $ make LIBTRACEEVENT_DYNAMIC=1 VF=1 O=/tmp/build/perf -C tools/perf install-bin |&amp; grep traceevent
  Makefile.config:1090: *** Error: No libtraceevent devel library found, please install libtraceevent-devel.  Stop.
  $

Signed-off-by: Michael Petlan &lt;mpetlan@redhat.com&gt;
Tested-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
LPU-Reference: 20210428092023.4009-1-mpetlan@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf stat: Enable iostat mode for x86 platforms</title>
<updated>2021-04-20T11:40:20+00:00</updated>
<author>
<name>Alexander Antonov</name>
<email>alexander.antonov@linux.intel.com</email>
</author>
<published>2021-04-19T09:41:46+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=f9ed693e8bc0e7de9eb766a3c7178590e8bb6cd5'/>
<id>f9ed693e8bc0e7de9eb766a3c7178590e8bb6cd5</id>
<content type='text'>
This functionality is based on recently introduced sysfs attributes for
Intel® Xeon® Scalable processor family (code name Skylake-SP):

Commit bb42b3d39781d7fc ("perf/x86/intel/uncore: Expose an Uncore unit to IIO PMON mapping")

Mode is intended to provide four I/O performance metrics in MB per each
PCIe root port:

 - Inbound Read: I/O devices below root port read from the host memory
 - Inbound Write: I/O devices below root port write to the host memory
 - Outbound Read: CPU reads from I/O devices below root port
 - Outbound Write: CPU writes to I/O devices below root port

Each metric requiries only one uncore event which increments at every 4B
transfer in corresponding direction. The formulas to compute metrics
are generic:
    #EventCount * 4B / (1024 * 1024)

Acked-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
Signed-off-by: Alexander Antonov &lt;alexander.antonov@linux.intel.com&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Alexey V Bayduraev &lt;alexey.v.bayduraev@linux.intel.com&gt;
Cc: Andi Kleen &lt;ak@linux.intel.com&gt;
Cc: Arnaldo Carvalho de Melo &lt;acme@kernel.org&gt;
Cc: Ian Rogers &lt;irogers@google.com&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Link: https://lore.kernel.org/r/20210419094147.15909-4-alexander.antonov@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This functionality is based on recently introduced sysfs attributes for
Intel® Xeon® Scalable processor family (code name Skylake-SP):

Commit bb42b3d39781d7fc ("perf/x86/intel/uncore: Expose an Uncore unit to IIO PMON mapping")

Mode is intended to provide four I/O performance metrics in MB per each
PCIe root port:

 - Inbound Read: I/O devices below root port read from the host memory
 - Inbound Write: I/O devices below root port write to the host memory
 - Outbound Read: CPU reads from I/O devices below root port
 - Outbound Write: CPU writes to I/O devices below root port

Each metric requiries only one uncore event which increments at every 4B
transfer in corresponding direction. The formulas to compute metrics
are generic:
    #EventCount * 4B / (1024 * 1024)

Acked-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
Signed-off-by: Alexander Antonov &lt;alexander.antonov@linux.intel.com&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Alexey V Bayduraev &lt;alexey.v.bayduraev@linux.intel.com&gt;
Cc: Andi Kleen &lt;ak@linux.intel.com&gt;
Cc: Arnaldo Carvalho de Melo &lt;acme@kernel.org&gt;
Cc: Ian Rogers &lt;irogers@google.com&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Link: https://lore.kernel.org/r/20210419094147.15909-4-alexander.antonov@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf stat: Introduce 'bperf' to share hardware PMCs with BPF</title>
<updated>2021-03-23T20:46:44+00:00</updated>
<author>
<name>Song Liu</name>
<email>songliubraving@fb.com</email>
</author>
<published>2021-03-16T21:18:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=7fac83aaf2eecc9e7e7b72da694c49bb4ce7fdfc'/>
<id>7fac83aaf2eecc9e7e7b72da694c49bb4ce7fdfc</id>
<content type='text'>
The perf tool uses performance monitoring counters (PMCs) to monitor
system performance. The PMCs are limited hardware resources. For
example, Intel CPUs have 3x fixed PMCs and 4x programmable PMCs per cpu.

Modern data center systems use these PMCs in many different ways: system
level monitoring, (maybe nested) container level monitoring, per process
monitoring, profiling (in sample mode), etc. In some cases, there are
more active perf_events than available hardware PMCs. To allow all
perf_events to have a chance to run, it is necessary to do expensive
time multiplexing of events.

On the other hand, many monitoring tools count the common metrics
(cycles, instructions). It is a waste to have multiple tools create
multiple perf_events of "cycles" and occupy multiple PMCs.

bperf tries to reduce such wastes by allowing multiple perf_events of
"cycles" or "instructions" (at different scopes) to share PMUs. Instead
of having each perf-stat session to read its own perf_events, bperf uses
BPF programs to read the perf_events and aggregate readings to BPF maps.
Then, the perf-stat session(s) reads the values from these BPF maps.

Please refer to the comment before the definition of bperf_ops for the
description of bperf architecture.

bperf is off by default. To enable it, pass --bpf-counters option to
perf-stat. bperf uses a BPF hashmap to share information about BPF
programs and maps used by bperf. This map is pinned to bpffs. The
default path is /sys/fs/bpf/perf_attr_map. The user could change the
path with option --bpf-attr-map.

Committer testing:

  # dmesg|grep "Performance Events" -A5
  [    0.225277] Performance Events: Fam17h+ core perfctr, AMD PMU driver.
  [    0.225280] ... version:                0
  [    0.225280] ... bit width:              48
  [    0.225281] ... generic registers:      6
  [    0.225281] ... value mask:             0000ffffffffffff
  [    0.225281] ... max period:             00007fffffffffff
  #
  #  for a in $(seq 6) ; do perf stat -a -e cycles,instructions sleep 100000 &amp; done
  [1] 2436231
  [2] 2436232
  [3] 2436233
  [4] 2436234
  [5] 2436235
  [6] 2436236
  # perf stat -a -e cycles,instructions sleep 0.1

   Performance counter stats for 'system wide':

         310,326,987      cycles                                                        (41.87%)
         236,143,290      instructions              #    0.76  insn per cycle           (41.87%)

         0.100800885 seconds time elapsed

  #

We can see that the counters were enabled for this workload 41.87% of
the time.

Now with --bpf-counters:

  #  for a in $(seq 32) ; do perf stat --bpf-counters -a -e cycles,instructions sleep 100000 &amp; done
  [1] 2436514
  [2] 2436515
  [3] 2436516
  [4] 2436517
  [5] 2436518
  [6] 2436519
  [7] 2436520
  [8] 2436521
  [9] 2436522
  [10] 2436523
  [11] 2436524
  [12] 2436525
  [13] 2436526
  [14] 2436527
  [15] 2436528
  [16] 2436529
  [17] 2436530
  [18] 2436531
  [19] 2436532
  [20] 2436533
  [21] 2436534
  [22] 2436535
  [23] 2436536
  [24] 2436537
  [25] 2436538
  [26] 2436539
  [27] 2436540
  [28] 2436541
  [29] 2436542
  [30] 2436543
  [31] 2436544
  [32] 2436545
  #
  # ls -la /sys/fs/bpf/perf_attr_map
  -rw-------. 1 root root 0 Mar 23 14:53 /sys/fs/bpf/perf_attr_map
  # bpftool map | grep bperf | wc -l
  64
  #

  # bpftool map | tail
  1265: percpu_array  name accum_readings  flags 0x0
  	key 4B  value 24B  max_entries 1  memlock 4096B
  1266: hash  name filter  flags 0x0
  	key 4B  value 4B  max_entries 1  memlock 4096B
  1267: array  name bperf_fo.bss  flags 0x400
  	key 4B  value 8B  max_entries 1  memlock 4096B
  	btf_id 996
  	pids perf(2436545)
  1268: percpu_array  name accum_readings  flags 0x0
  	key 4B  value 24B  max_entries 1  memlock 4096B
  1269: hash  name filter  flags 0x0
  	key 4B  value 4B  max_entries 1  memlock 4096B
  1270: array  name bperf_fo.bss  flags 0x400
  	key 4B  value 8B  max_entries 1  memlock 4096B
  	btf_id 997
  	pids perf(2436541)
  1285: array  name pid_iter.rodata  flags 0x480
  	key 4B  value 4B  max_entries 1  memlock 4096B
  	btf_id 1017  frozen
  	pids bpftool(2437504)
  1286: array  flags 0x0
  	key 4B  value 32B  max_entries 1  memlock 4096B
  #
  # bpftool map dump id 1268 | tail
  value (CPU 21):
  8f f3 bc ca 00 00 00 00  80 fd 2a d1 4d 00 00 00
  80 fd 2a d1 4d 00 00 00
  value (CPU 22):
  7e d5 64 4d 00 00 00 00  a4 8a 2e ee 4d 00 00 00
  a4 8a 2e ee 4d 00 00 00
  value (CPU 23):
  a7 78 3e 06 01 00 00 00  b2 34 94 f6 4d 00 00 00
  b2 34 94 f6 4d 00 00 00
  Found 1 element
  # bpftool map dump id 1268 | tail
  value (CPU 21):
  c6 8b d9 ca 00 00 00 00  20 c6 fc 83 4e 00 00 00
  20 c6 fc 83 4e 00 00 00
  value (CPU 22):
  9c b4 d2 4d 00 00 00 00  3e 0c df 89 4e 00 00 00
  3e 0c df 89 4e 00 00 00
  value (CPU 23):
  18 43 66 06 01 00 00 00  5b 69 ed 83 4e 00 00 00
  5b 69 ed 83 4e 00 00 00
  Found 1 element
  # bpftool map dump id 1268 | tail
  value (CPU 21):
  f2 6e db ca 00 00 00 00  92 67 4c ba 4e 00 00 00
  92 67 4c ba 4e 00 00 00
  value (CPU 22):
  dc 8e e1 4d 00 00 00 00  d9 32 7a c5 4e 00 00 00
  d9 32 7a c5 4e 00 00 00
  value (CPU 23):
  bd 2b 73 06 01 00 00 00  7c 73 87 bf 4e 00 00 00
  7c 73 87 bf 4e 00 00 00
  Found 1 element
  #

  # perf stat --bpf-counters -a -e cycles,instructions sleep 0.1

   Performance counter stats for 'system wide':

       119,410,122      cycles
       152,105,479      instructions              #    1.27  insn per cycle

       0.101395093 seconds time elapsed

  #

See? We had the counters enabled all the time.

Signed-off-by: Song Liu &lt;songliubraving@fb.com&gt;
Reviewed-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Acked-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
Tested-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Cc: kernel-team@fb.com
Link: http://lore.kernel.org/lkml/20210316211837.910506-2-songliubraving@fb.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The perf tool uses performance monitoring counters (PMCs) to monitor
system performance. The PMCs are limited hardware resources. For
example, Intel CPUs have 3x fixed PMCs and 4x programmable PMCs per cpu.

Modern data center systems use these PMCs in many different ways: system
level monitoring, (maybe nested) container level monitoring, per process
monitoring, profiling (in sample mode), etc. In some cases, there are
more active perf_events than available hardware PMCs. To allow all
perf_events to have a chance to run, it is necessary to do expensive
time multiplexing of events.

On the other hand, many monitoring tools count the common metrics
(cycles, instructions). It is a waste to have multiple tools create
multiple perf_events of "cycles" and occupy multiple PMCs.

bperf tries to reduce such wastes by allowing multiple perf_events of
"cycles" or "instructions" (at different scopes) to share PMUs. Instead
of having each perf-stat session to read its own perf_events, bperf uses
BPF programs to read the perf_events and aggregate readings to BPF maps.
Then, the perf-stat session(s) reads the values from these BPF maps.

Please refer to the comment before the definition of bperf_ops for the
description of bperf architecture.

bperf is off by default. To enable it, pass --bpf-counters option to
perf-stat. bperf uses a BPF hashmap to share information about BPF
programs and maps used by bperf. This map is pinned to bpffs. The
default path is /sys/fs/bpf/perf_attr_map. The user could change the
path with option --bpf-attr-map.

Committer testing:

  # dmesg|grep "Performance Events" -A5
  [    0.225277] Performance Events: Fam17h+ core perfctr, AMD PMU driver.
  [    0.225280] ... version:                0
  [    0.225280] ... bit width:              48
  [    0.225281] ... generic registers:      6
  [    0.225281] ... value mask:             0000ffffffffffff
  [    0.225281] ... max period:             00007fffffffffff
  #
  #  for a in $(seq 6) ; do perf stat -a -e cycles,instructions sleep 100000 &amp; done
  [1] 2436231
  [2] 2436232
  [3] 2436233
  [4] 2436234
  [5] 2436235
  [6] 2436236
  # perf stat -a -e cycles,instructions sleep 0.1

   Performance counter stats for 'system wide':

         310,326,987      cycles                                                        (41.87%)
         236,143,290      instructions              #    0.76  insn per cycle           (41.87%)

         0.100800885 seconds time elapsed

  #

We can see that the counters were enabled for this workload 41.87% of
the time.

Now with --bpf-counters:

  #  for a in $(seq 32) ; do perf stat --bpf-counters -a -e cycles,instructions sleep 100000 &amp; done
  [1] 2436514
  [2] 2436515
  [3] 2436516
  [4] 2436517
  [5] 2436518
  [6] 2436519
  [7] 2436520
  [8] 2436521
  [9] 2436522
  [10] 2436523
  [11] 2436524
  [12] 2436525
  [13] 2436526
  [14] 2436527
  [15] 2436528
  [16] 2436529
  [17] 2436530
  [18] 2436531
  [19] 2436532
  [20] 2436533
  [21] 2436534
  [22] 2436535
  [23] 2436536
  [24] 2436537
  [25] 2436538
  [26] 2436539
  [27] 2436540
  [28] 2436541
  [29] 2436542
  [30] 2436543
  [31] 2436544
  [32] 2436545
  #
  # ls -la /sys/fs/bpf/perf_attr_map
  -rw-------. 1 root root 0 Mar 23 14:53 /sys/fs/bpf/perf_attr_map
  # bpftool map | grep bperf | wc -l
  64
  #

  # bpftool map | tail
  1265: percpu_array  name accum_readings  flags 0x0
  	key 4B  value 24B  max_entries 1  memlock 4096B
  1266: hash  name filter  flags 0x0
  	key 4B  value 4B  max_entries 1  memlock 4096B
  1267: array  name bperf_fo.bss  flags 0x400
  	key 4B  value 8B  max_entries 1  memlock 4096B
  	btf_id 996
  	pids perf(2436545)
  1268: percpu_array  name accum_readings  flags 0x0
  	key 4B  value 24B  max_entries 1  memlock 4096B
  1269: hash  name filter  flags 0x0
  	key 4B  value 4B  max_entries 1  memlock 4096B
  1270: array  name bperf_fo.bss  flags 0x400
  	key 4B  value 8B  max_entries 1  memlock 4096B
  	btf_id 997
  	pids perf(2436541)
  1285: array  name pid_iter.rodata  flags 0x480
  	key 4B  value 4B  max_entries 1  memlock 4096B
  	btf_id 1017  frozen
  	pids bpftool(2437504)
  1286: array  flags 0x0
  	key 4B  value 32B  max_entries 1  memlock 4096B
  #
  # bpftool map dump id 1268 | tail
  value (CPU 21):
  8f f3 bc ca 00 00 00 00  80 fd 2a d1 4d 00 00 00
  80 fd 2a d1 4d 00 00 00
  value (CPU 22):
  7e d5 64 4d 00 00 00 00  a4 8a 2e ee 4d 00 00 00
  a4 8a 2e ee 4d 00 00 00
  value (CPU 23):
  a7 78 3e 06 01 00 00 00  b2 34 94 f6 4d 00 00 00
  b2 34 94 f6 4d 00 00 00
  Found 1 element
  # bpftool map dump id 1268 | tail
  value (CPU 21):
  c6 8b d9 ca 00 00 00 00  20 c6 fc 83 4e 00 00 00
  20 c6 fc 83 4e 00 00 00
  value (CPU 22):
  9c b4 d2 4d 00 00 00 00  3e 0c df 89 4e 00 00 00
  3e 0c df 89 4e 00 00 00
  value (CPU 23):
  18 43 66 06 01 00 00 00  5b 69 ed 83 4e 00 00 00
  5b 69 ed 83 4e 00 00 00
  Found 1 element
  # bpftool map dump id 1268 | tail
  value (CPU 21):
  f2 6e db ca 00 00 00 00  92 67 4c ba 4e 00 00 00
  92 67 4c ba 4e 00 00 00
  value (CPU 22):
  dc 8e e1 4d 00 00 00 00  d9 32 7a c5 4e 00 00 00
  d9 32 7a c5 4e 00 00 00
  value (CPU 23):
  bd 2b 73 06 01 00 00 00  7c 73 87 bf 4e 00 00 00
  7c 73 87 bf 4e 00 00 00
  Found 1 element
  #

  # perf stat --bpf-counters -a -e cycles,instructions sleep 0.1

   Performance counter stats for 'system wide':

       119,410,122      cycles
       152,105,479      instructions              #    1.27  insn per cycle

       0.101395093 seconds time elapsed

  #

See? We had the counters enabled all the time.

Signed-off-by: Song Liu &lt;songliubraving@fb.com&gt;
Reviewed-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Acked-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
Tested-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Cc: kernel-team@fb.com
Link: http://lore.kernel.org/lkml/20210316211837.910506-2-songliubraving@fb.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge remote-tracking branch 'torvalds/master' into perf/core</title>
<updated>2021-03-08T13:11:33+00:00</updated>
<author>
<name>Arnaldo Carvalho de Melo</name>
<email>acme@redhat.com</email>
</author>
<published>2021-03-08T13:11:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=009ef05f98129aa91c62c3baab859ba593a15bb2'/>
<id>009ef05f98129aa91c62c3baab859ba593a15bb2</id>
<content type='text'>
To pick up the fixes sent for v5.12 and continue development based on
v5.12-rc2, i.e. without the swap on file bug.

This also gets a slightly newer and better tools/perf/arch/arm/util/cs-etm.c
patch version, using the BIT() macro, that had already been slated to
v5.13 but ended up going to v5.12-rc1 on an older version.

Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
To pick up the fixes sent for v5.12 and continue development based on
v5.12-rc2, i.e. without the swap on file bug.

This also gets a slightly newer and better tools/perf/arch/arm/util/cs-etm.c
patch version, using the BIT() macro, that had already been slated to
v5.13 but ended up going to v5.12-rc1 on an older version.

Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf build: Fix ccache usage in $(CC) when generating arch errno table</title>
<updated>2021-03-06T19:54:26+00:00</updated>
<author>
<name>Antonio Terceiro</name>
<email>antonio.terceiro@linaro.org</email>
</author>
<published>2021-02-24T13:00:46+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=dacfc08dcafa7d443ab339592999e37bbb8a3ef0'/>
<id>dacfc08dcafa7d443ab339592999e37bbb8a3ef0</id>
<content type='text'>
This was introduced by commit e4ffd066ff440a57 ("perf: Normalize gcc
parameter when generating arch errno table").

Assuming the first word of $(CC) is the actual compiler breaks usage
like CC="ccache gcc": the script ends up calling ccache directly with
gcc arguments, what fails. Instead of getting the first word, just
remove from $(CC) any word that starts with a "-". This maintains the
spirit of the original patch, while not breaking ccache users.

Fixes: e4ffd066ff440a57 ("perf: Normalize gcc parameter when generating arch errno table")
Signed-off-by: Antonio Terceiro &lt;antonio.terceiro@linaro.org&gt;
Tested-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: He Zhe &lt;zhe.he@windriver.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: stable@vger.kernel.org
Link: http://lore.kernel.org/lkml/20210224130046.346977-1-antonio.terceiro@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This was introduced by commit e4ffd066ff440a57 ("perf: Normalize gcc
parameter when generating arch errno table").

Assuming the first word of $(CC) is the actual compiler breaks usage
like CC="ccache gcc": the script ends up calling ccache directly with
gcc arguments, what fails. Instead of getting the first word, just
remove from $(CC) any word that starts with a "-". This maintains the
spirit of the original patch, while not breaking ccache users.

Fixes: e4ffd066ff440a57 ("perf: Normalize gcc parameter when generating arch errno table")
Signed-off-by: Antonio Terceiro &lt;antonio.terceiro@linaro.org&gt;
Tested-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: He Zhe &lt;zhe.he@windriver.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: stable@vger.kernel.org
Link: http://lore.kernel.org/lkml/20210224130046.346977-1-antonio.terceiro@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf build: Move feature cleanup under tools/build</title>
<updated>2021-03-06T19:54:24+00:00</updated>
<author>
<name>Jiri Olsa</name>
<email>jolsa@kernel.org</email>
</author>
<published>2021-02-24T15:08:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=762323eb39a257c3b9875172d5ee134bd448692c'/>
<id>762323eb39a257c3b9875172d5ee134bd448692c</id>
<content type='text'>
Arnaldo reported issue for following build command:

  $ rm -rf /tmp/krava; mkdir /tmp/krava; make O=/tmp/krava clean
    CLEAN    config
  /bin/sh: line 0: cd: /tmp/krava/feature/: No such file or directory
  ../../scripts/Makefile.include:17: *** output directory "/tmp/krava/feature/" does not exist.  Stop.
  make[1]: *** [Makefile.perf:1010: config-clean] Error 2
  make: *** [Makefile:90: clean] Error 2

The problem is that now that we include scripts/Makefile.include
in feature's Makefile (which is fine and needed), we need to ensure
the OUTPUT directory exists, before executing (out of tree) clean
command.

Removing the feature's cleanup from perf Makefile and fixing
feature's cleanup under build Makefile, so it now checks that
there's existing OUTPUT directory before calling the clean.

Fixes: 211a741cd3e1 ("tools: Factor Clang, LLC and LLVM utils definitions")
Reported-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Tested-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Tested-by: Sedat Dilek &lt;sedat.dilek@gmail.com&gt; # LLVM/Clang v13-git
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Ian Rogers &lt;irogers@google.com&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Michael Petlan &lt;mpetlan@redhat.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Link: http://lore.kernel.org/lkml/20210224150831.409639-1-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Arnaldo reported issue for following build command:

  $ rm -rf /tmp/krava; mkdir /tmp/krava; make O=/tmp/krava clean
    CLEAN    config
  /bin/sh: line 0: cd: /tmp/krava/feature/: No such file or directory
  ../../scripts/Makefile.include:17: *** output directory "/tmp/krava/feature/" does not exist.  Stop.
  make[1]: *** [Makefile.perf:1010: config-clean] Error 2
  make: *** [Makefile:90: clean] Error 2

The problem is that now that we include scripts/Makefile.include
in feature's Makefile (which is fine and needed), we need to ensure
the OUTPUT directory exists, before executing (out of tree) clean
command.

Removing the feature's cleanup from perf Makefile and fixing
feature's cleanup under build Makefile, so it now checks that
there's existing OUTPUT directory before calling the clean.

Fixes: 211a741cd3e1 ("tools: Factor Clang, LLC and LLVM utils definitions")
Reported-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Tested-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Tested-by: Sedat Dilek &lt;sedat.dilek@gmail.com&gt; # LLVM/Clang v13-git
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Ian Rogers &lt;irogers@google.com&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Michael Petlan &lt;mpetlan@redhat.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Link: http://lore.kernel.org/lkml/20210224150831.409639-1-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf tools: Enable warnings when compiling BPF programs</title>
<updated>2021-03-06T19:42:16+00:00</updated>
<author>
<name>Ian Rogers</name>
<email>irogers@google.com</email>
</author>
<published>2021-03-06T08:08:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=7e1df64edeb294767f0976a7784fe1dbbe9f4394'/>
<id>7e1df64edeb294767f0976a7784fe1dbbe9f4394</id>
<content type='text'>
Add -Wall -Werror when compiling BPF skeletons.

Signed-off-by: Ian Rogers &lt;irogers@google.com&gt;
Acked-by: Song Liu &lt;songliubraving@fb.com&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Stephane Eranian &lt;eranian@google.com&gt;
Link: http://lore.kernel.org/lkml/20210306080840.3785816-2-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Add -Wall -Werror when compiling BPF skeletons.

Signed-off-by: Ian Rogers &lt;irogers@google.com&gt;
Acked-by: Song Liu &lt;songliubraving@fb.com&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Stephane Eranian &lt;eranian@google.com&gt;
Link: http://lore.kernel.org/lkml/20210306080840.3785816-2-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</pre>
</div>
</content>
</entry>
</feed>
