Commits · 2a09a84c720b436a3ded9b7e3701d391ec81892a · Kirill Smelkov / linux

14 Oct, 2020 18 commits

perf diff: Support hot streams comparison · 2a09a84c

Jin Yao authored Oct 09, 2020

This patch enables perf-diff with "--stream" option.

"--stream": Enable hot streams comparison

Now let's see example.

perf record -b ...      Generate perf.data.old with branch data
perf record -b ...      Generate perf.data with branch data
perf diff --stream

[ Matched hot streams ]

hot chain pair 1:
            cycles: 1, hits: 27.77%                  cycles: 1, hits: 9.24%
        ---------------------------              --------------------------
                      main div.c:39                           main div.c:39
                      main div.c:44                           main div.c:44

hot chain pair 2:
           cycles: 34, hits: 20.06%                cycles: 27, hits: 16.98%
        ---------------------------              --------------------------
          __random_r random_r.c:360               __random_r random_r.c:360
          __random_r random_r.c:388               __random_r random_r.c:388
          __random_r random_r.c:388               __random_r random_r.c:388
          __random_r random_r.c:380               __random_r random_r.c:380
          __random_r random_r.c:357               __random_r random_r.c:357
              __random random.c:293                   __random random.c:293
              __random random.c:293                   __random random.c:293
              __random random.c:291                   __random random.c:291
              __random random.c:291                   __random random.c:291
              __random random.c:291                   __random random.c:291
              __random random.c:288                   __random random.c:288
                     rand rand.c:27                          rand rand.c:27
                     rand rand.c:26                          rand rand.c:26
                           rand@plt                                rand@plt
                           rand@plt                                rand@plt
              compute_flag div.c:25                   compute_flag div.c:25
              compute_flag div.c:22                   compute_flag div.c:22
                      main div.c:40                           main div.c:40
                      main div.c:40                           main div.c:40
                      main div.c:39                           main div.c:39

hot chain pair 3:
             cycles: 9, hits: 4.48%                  cycles: 6, hits: 4.51%
        ---------------------------              --------------------------
          __random_r random_r.c:360               __random_r random_r.c:360
          __random_r random_r.c:388               __random_r random_r.c:388
          __random_r random_r.c:388               __random_r random_r.c:388
          __random_r random_r.c:380               __random_r random_r.c:380

[ Hot streams in old perf data only ]

hot chain 1:
            cycles: 18, hits: 6.75%
         --------------------------
          __random_r random_r.c:360
          __random_r random_r.c:388
          __random_r random_r.c:388
          __random_r random_r.c:380
          __random_r random_r.c:357
              __random random.c:293
              __random random.c:293
              __random random.c:291
              __random random.c:291
              __random random.c:291
              __random random.c:288
                     rand rand.c:27
                     rand rand.c:26
                           rand@plt
                           rand@plt
              compute_flag div.c:25
              compute_flag div.c:22
                      main div.c:40

hot chain 2:
            cycles: 29, hits: 2.78%
         --------------------------
              compute_flag div.c:22
                      main div.c:40
                      main div.c:40
                      main div.c:39

[ Hot streams in new perf data only ]

hot chain 1:
                                                     cycles: 4, hits: 4.54%
                                                 --------------------------
                                                              main div.c:42
                                                      compute_flag div.c:28

hot chain 2:
                                                     cycles: 5, hits: 3.51%
                                                 --------------------------
                                                              main div.c:39
                                                              main div.c:44
                                                              main div.c:42
                                                      compute_flag div.c:28
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20201009022845.13141-8-yao.jin@linux.intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2a09a84c

perf streams: Report hot streams · 5bbd6bad

Jin Yao authored Oct 09, 2020

We show the streams separately. They are divided into different sections.

1. "Matched hot streams"

2. "Hot streams in old perf data only"

3. "Hot streams in new perf data only".

For each stream, we report the cycles and hot percent (hits%).

For example,

     cycles: 2, hits: 4.08%
 --------------------------
              main div.c:42
      compute_flag div.c:28
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20201009022845.13141-7-yao.jin@linux.intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

5bbd6bad

perf streams: Calculate the sum of total streams hits · 28904f4d

Jin Yao authored Oct 09, 2020

We have used callchain_node->hit to measure the hot level of one stream.
This patch calculates the sum of hits of total streams.

Thus in next patch, we can use following formula to report hot percent
for one stream.

hot percent = callchain_node->hit / sum of total hits
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20201009022845.13141-6-yao.jin@linux.intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

28904f4d

perf streams: Link stream pair · fa79aa64

Jin Yao authored Oct 09, 2020

In previous patch, we have created an evsel_streams for one event, and
top N hottest streams will be saved in a stream array in evsel_streams.

This patch compares total streams among two evsel_streams.

Once two streams are fully matched, they will be linked as a pair. From
the pair, we can know which streams are matched.
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20201009022845.13141-5-yao.jin@linux.intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

fa79aa64

perf streams: Compare two streams · 47ef8398

Jin Yao authored Oct 09, 2020

Stream is the branch history which is aggregated by the branch records
from perf samples. Now we support the callchain as stream.

If the callchain entries of one stream are fully matched with the
callchain entries of another stream, we think two streams are matched.

For example,

   cycles: 1, hits: 26.80%                 cycles: 1, hits: 27.30%
   -----------------------                 -----------------------
             main div.c:39                           main div.c:39
             main div.c:44                           main div.c:44

Above two streams are matched (we don't consider the case that source
code is changed).

The matching logic is, compare the chain string first. If it's not
matched, fallback to dso address comparison.
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20201009022845.13141-4-yao.jin@linux.intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

47ef8398

perf streams: Get the evsel_streams by evsel_idx · dd1d8418

Jin Yao authored Oct 09, 2020

In previous patch, we have created evsel_streams array.

This patch returns the specified evsel_streams according to the
evsel_idx.
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20201009022845.13141-3-yao.jin@linux.intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

dd1d8418

perf streams: Introduce branch history "streams" · 480accbb

Jin Yao authored Oct 09, 2020

We define a stream as the branch history which is aggregated by the
branch records from perf samples. For example, the callchains aggregated
from the branch records are considered as streams. By browsing the hot
stream, we can understand the hot code path.

Now we only support the callchain for stream. For measuring the hot
level for a stream, we use the callchain_node->hit, higher is hotter.

There may be many callchains sampled so we only focus on the top N
hottest callchains. N is a user defined parameter or predefined default
value (nr_streams_max).

This patch creates an evsel_streams array per event, and saves the top N
hottest streams in a stream array.

So now we can get the per-event top N hottest streams.
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20201009022845.13141-2-yao.jin@linux.intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

480accbb

perf intel-pt: Improve PT documentation slightly · 6556a75b

Andi Kleen authored Oct 13, 2020

Document the higher level --insn-trace etc. perf script options.

Include the howto how to build xed into the manpage
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lore.kernel.org/lkml/20201014035346.4772-1-andi@firstfloor.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

6556a75b

perf tools: Add support for exclusive groups/events · 0997a266

Andi Kleen authored Oct 14, 2020

Peter suggested that using the exclusive mode in perf could avoid some
problems with bad scheduling of groups. Exclusive is implemented in the
kernel, but wasn't exposed by the perf tool, so hard to use without
custom low level API users.

Add support for marking groups or events with :e for exclusive in the
perf tool.  The implementation is basically the same as the existing
pinned attribute.

Committer testing:

  # perf test "parse event"
   6: Parse event definition strings                                  : Ok
  # perf test -v "parse event" |& grep :u*e
  running test 56 'instructions:uep'
  running test 57 '{cycles,cache-misses,branch-misses}:e'
  #
  #
  # grep "model name" -m1 /proc/cpuinfo
  model name	: AMD Ryzen 9 3900X 12-Core Processor
  #
  # perf stat -a -e '{cycles,cache-misses,branch-misses}:e' sleep 1

   Performance counter stats for 'system wide':

       <not counted>      cycles                                                        (0.00%)
       <not counted>      cache-misses                                                  (0.00%)
       <not counted>      branch-misses                                                 (0.00%)

         1.001269893 seconds time elapsed

  Some events weren't counted. Try disabling the NMI watchdog:
  	echo 0 > /proc/sys/kernel/nmi_watchdog
  	perf stat ...
  	echo 1 > /proc/sys/kernel/nmi_watchdog
  # echo 0 > /proc/sys/kernel/nmi_watchdog
  # perf stat -a -e '{cycles,cache-misses,branch-misses}:e' sleep 1

   Performance counter stats for 'system wide':

       1,298,663,141      cycles
          30,962,215      cache-misses
           5,325,150      branch-misses

         1.001474934 seconds time elapsed

  #
  # The output for asking for precise events on AMD needs to improve, it
  # supposedly works only for system wide or per CPU
  #
  # perf stat -a -e '{cycles,cache-misses,branch-misses}:uep' sleep 1
  Error:
  The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (cycles).
  /bin/dmesg | grep -i perf may provide additional information.

  # perf stat -a -e '{cycles,cache-misses,branch-misses}:ue' sleep 1

   Performance counter stats for 'system wide':

         746,363,126      cycles
          16,881,611      cache-misses
           2,871,259      branch-misses

         1.001636066 seconds time elapsed

  #
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20201014144255.22699-1-andi@firstfloor.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

0997a266