1. 24 Jun, 2023 2 commits
    • Namhyung Kim's avatar
      perf test: Skip metrics w/o event name in stat STD output linter · 4d60e83d
      Namhyung Kim authored
      This test checks if the output of perf stat to match event names and
      metrics.  So it wants the output lines to have both event name and
      metric.  Otherwise it should skip the line.
      
      On AMD machines, the instruction event has two metrics and they are printed
      in separate lines.  It makes the line without event name like below:
      
        # perf stat -a sleep 1
      
         Performance counter stats for 'system wide':
      
                 64,383.34 msec cpu-clock                  #   64.048 CPUs utilized
                    14,526      context-switches           #  225.617 /sec
                       112      cpu-migrations             #    1.740 /sec
                       190      page-faults                #    2.951 /sec
               807,558,652      cycles                     #    0.013 GHz                         (83.30%)
                69,809,799      stalled-cycles-frontend    #    8.64% frontend cycles idle        (83.30%)
               196,983,266      stalled-cycles-backend     #   24.39% backend cycles idle         (83.30%)
               424,876,008      instructions               #    0.53  insn per cycle
       (here) --->                                  #    0.46  stalled cycles per insn     (83.30%)
                97,788,321      branches                   #    1.519 M/sec                       (83.34%)
                 4,147,377      branch-misses              #    4.24% of all branches             (83.46%)
      
               1.005241409 seconds time elapsed
      
      Also modern Intel machines have TopDown metrics which also don't have
      event names.
      
        # perf stat -a sleep 1
      
         Performance counter stats for 'system wide':
      
                  8,015.39 msec cpu-clock                        #    7.996 CPUs utilized
                     5,823      context-switches                 #  726.477 /sec
                       189      cpu-migrations                   #   23.580 /sec
                       139      page-faults                      #   17.342 /sec
               435,139,308      cycles                           #    0.054 GHz
               193,891,345      instructions                     #    0.45  insn per cycle
                42,773,028      branches                         #    5.336 M/sec
                 2,298,113      branch-misses                    #    5.37% of all branches
                                TopdownL1                 #     25.5 %  tma_backend_bound
                    /-->                                  #      7.9 %  tma_bad_speculation
          (here) --+                                      #     55.7 %  tma_frontend_bound
                    \-->                                  #     10.9 %  tma_retiring
      
               1.002395924 seconds time elapsed
      
      There is a check to skip TopdownL1 and TopdownL2 specifically but it
      does not cover every affected lines.
      
      So there is another check to skip the line if it has nothing on the left
      side of # sign.  Well.. it seems ok but that's not enough too.
      
      When aggregation mode (like --per-socket or --per-thread) is used, it
      adds some prefix (e.g. CPU socket, task name and PID) in the output
      line.  So the test code ignores them to normalize result.
      
      A problem can happen for per-thread mode when task name contains one or
      more spaces.  It'd only ignore the first part of the task name, and it
      thinks there's something more in the line so it would not skip.
      
        # perf stat -a --perf-thread sleep 1
        ...
                  perf-21276                  #     70.2 %  tma_backend_bound
                  perf-21276                  #      3.9 %  tma_bad_speculation
                  perf-21276                  #     10.5 %  tma_frontend_bound
                  perf-21276                  #     15.3 %  tma_retiring
      	    ^^^^^^^^^^
      	    (ignored)
      
               my task-21328                  #     70.2 %  tma_backend_bound
               my task-21328                  #      3.9 %  tma_bad_speculation
               my task-21328                  #     10.5 %  tma_frontend_bound
               my task-21328                  #     15.3 %  tma_retiring
      	 ^^
           (ignored)
      
      So I think it should look at the metric names instead.  Add skip_metric
      to hold the list of names to skip.  It would contain 'stalled cycles per
      insn' and metrics started by 'tma_'.
      
      Fixes: 99a04a48 ("perf test: Add test case for the standard 'perf stat' output")
      Acked-by: default avatarIan Rogers <irogers@google.com>
      Cc: Kan Liang <kan.liang@linux.intel.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Adrian Hunter <adrian.hunter@intel.com>
      Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
      Cc: Jiri Olsa <jolsa@kernel.org>
      Cc: Ingo Molnar <mingo@kernel.org>
      Link: https://lore.kernel.org/r/20230623230139.985594-2-namhyung@kernel.orgSigned-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
      4d60e83d
    • Namhyung Kim's avatar
      perf test: Reorder event name checks in stat STD output linter · 8d3df7c3
      Namhyung Kim authored
      On AMD machines, the perf stat STD output test failed like below:
      
        $ sudo ./perf test -v 98
         98: perf stat STD output linter                                     :
        --- start ---
        test child forked, pid 1841901
        Checking STD output: no argswrong event metric.
          expected 'GHz' in 108,121 stalled-cycles-frontend  # 10.88% frontend cycles idle
        test child finished with -1
        ---- end ----
        perf stat STD output linter: FAILED!
      
      This is because there are stalled-cycles-{frontend,backend} events are
      used by default.  The current logic checks the event_name array to find
      which event it's running.  But 'cycles' event comes before those stalled
      cycles event and it matches first.  So it tries to find 'GHz' metric
      in the output (which is for the 'cycles') and fails.
      
      Move the stalled-cycles-{frontend,backend} events before 'cycles' so
      that it can find the stalled cycles events first.
      
      Also add a space after 'no args' test name for consistency.
      
      Fixes: 99a04a48 ("perf test: Add test case for the standard 'perf stat' output")
      Acked-by: default avatarIan Rogers <irogers@google.com>
      Cc: Kan Liang <kan.liang@linux.intel.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Adrian Hunter <adrian.hunter@intel.com>
      Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
      Cc: Jiri Olsa <jolsa@kernel.org>
      Cc: Ingo Molnar <mingo@kernel.org>
      Link: https://lore.kernel.org/r/20230623230139.985594-1-namhyung@kernel.orgSigned-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
      8d3df7c3
  2. 23 Jun, 2023 6 commits
    • Ian Rogers's avatar
      perf pmu: Remove a hard coded cpu PMU assumption · d06593aa
      Ian Rogers authored
      The property of "cpu" when it has no cpu map is true on S390 with the
      PMU cpum_cf. Rather than maintain a list of such PMUs, reuse the
      is_core test result from the caller.
      Signed-off-by: default avatarIan Rogers <irogers@google.com>
      Tested-by: default avatarThomas Richter <tmricht@linux.ibm.com>
      Cc: Ravi Bangoria <ravi.bangoria@amd.com>
      Cc: James Clark <james.clark@arm.com>
      Cc: Mark Rutland <mark.rutland@arm.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Adrian Hunter <adrian.hunter@intel.com>
      Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
      Cc: Jiri Olsa <jolsa@kernel.org>
      Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
      Cc: Kan Liang <kan.liang@linux.intel.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: linux-kernel@vger.kernel.org
      Cc: linux-perf-users@vger.kernel.org
      Link: https://lore.kernel.org/r/20230623043843.4080180-2-irogers@google.comSigned-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
      d06593aa
    • Ian Rogers's avatar
      perf pmus: Add notion of default PMU for JSON events · d685819b
      Ian Rogers authored
      JSON events created in pmu-events.c by jevents.py may not specify a
      PMU they are associated with, in which case it is implied that it is
      the first core PMU. Care is needed to select this for regular 'cpu',
      s390 'cpum_cf' and ARMs many names as at the point the name is first
      needed the core PMUs list hasn't been initialized. Add a helper in
      perf_pmus to create this value, in the worst case by scanning sysfs.
      
      v2. Add missing close if fdopendir fails.
      Signed-off-by: default avatarIan Rogers <irogers@google.com>
      Tested-by: default avatarThomas Richter <tmricht@linux.ibm.com>
      Cc: Ravi Bangoria <ravi.bangoria@amd.com>
      Cc: James Clark <james.clark@arm.com>
      Cc: Mark Rutland <mark.rutland@arm.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Adrian Hunter <adrian.hunter@intel.com>
      Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
      Cc: Jiri Olsa <jolsa@kernel.org>
      Cc: Thomas Richter <tmricht@linux.ibm.com>
      Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
      Cc: Kan Liang <kan.liang@linux.intel.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Link: https://lore.kernel.org/r/20230623043843.4080180-1-irogers@google.comSigned-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
      d685819b
    • Ian Rogers's avatar
      perf unwind: Fix map reference counts · 33941dbd
      Ian Rogers authored
      The result of thread__find_map is the map in the passed in
      addr_location. Calling addr_location__exit puts that map and so copies
      need to do a map__get. Add in the corresponding map__puts.
      
      v2. Add missing map__put when dso is missing.
      Signed-off-by: default avatarIan Rogers <irogers@google.com>
      Acked-by: default avatarNamhyung Kim <namhyung@kernel.org>
      Cc: Mark Rutland <mark.rutland@arm.com>
      Cc: Ivan Babrou <ivan@cloudflare.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Adrian Hunter <adrian.hunter@intel.com>
      Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
      Cc: Jiri Olsa <jolsa@kernel.org>
      Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Link: https://lore.kernel.org/r/20230623043107.4077510-1-irogers@google.comSigned-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
      33941dbd
    • Namhyung Kim's avatar
      perf test: Set PERF_EXEC_PATH for script execution · e4ef3ef1
      Namhyung Kim authored
      The task-analyzer.py script (actually every other scripts too) requires
      PERF_EXEC_PATH env to find dependent libraries and scripts. For scripts
      test to run correctly, it needs to set PERF_EXEC_PATH to the perf tool
      source directory.
      
      Instead of blindly update the env, let's check the directory structure
      to make sure it points to the correct location.
      
      Fixes: e8478b84 ("perf test: add new task-analyzer tests")
      Cc: Petar Gligoric <petar.gligoric@rohde-schwarz.com>
      Cc: Hagen Paul Pfeifer <hagen@jauu.net>
      Cc: Aditya Gupta <adityag@linux.ibm.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Adrian Hunter <adrian.hunter@intel.com>
      Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
      Cc: Jiri Olsa <jolsa@kernel.org>
      Cc: Ingo Molnar <mingo@kernel.org>
      Acked-by: default avatarIan Rogers <irogers@google.com>
      Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
      e4ef3ef1
    • Namhyung Kim's avatar
      perf script: Initialize buffer for regs_map() · 2d7f5540
      Namhyung Kim authored
      The buffer is used to save register mapping in a sample.  Normally
      perf samples don't have any register so the string should be empty.
      But it missed to initialize the buffer when the size is 0.  And it's
      passed to PyUnicode_FromString() with a garbage data.
      
      So it returns NULL due to invalid input (instead of an empty unicode
      string object) which causes a segfault like below:
      
        Thread 2.1 "perf" received signal SIGSEGV, Segmentation fault.
        [Switching to Thread 0x7ffff7c83780 (LWP 193775)]
        0x00007ffff6dbca2e in PyDict_SetItem () from /lib/x86_64-linux-gnu/libpython3.11.so.1.0
        (gdb) bt
        #0  0x00007ffff6dbca2e in PyDict_SetItem () from /lib/x86_64-linux-gnu/libpython3.11.so.1.0
        #1  0x00007ffff6dbf848 in PyDict_SetItemString () from /lib/x86_64-linux-gnu/libpython3.11.so.1.0
        #2  0x000055555575824d in pydict_set_item_string_decref (val=0x0, key=0x5555557f96e3 "iregs", dict=0x7ffff5f7f780)
            at util/scripting-engines/trace-event-python.c:145
        #3  set_regs_in_dict (evsel=0x555555efc370, sample=0x7fffffffb870, dict=0x7ffff5f7f780)
            at util/scripting-engines/trace-event-python.c:776
        #4  get_perf_sample_dict (sample=sample@entry=0x7fffffffb870, evsel=evsel@entry=0x555555efc370, al=al@entry=0x7fffffffb2e0,
            addr_al=addr_al@entry=0x0, callchain=callchain@entry=0x7ffff63ef440) at util/scripting-engines/trace-event-python.c:923
        #5  0x0000555555758ec1 in python_process_tracepoint (sample=0x7fffffffb870, evsel=0x555555efc370, al=0x7fffffffb2e0, addr_al=0x0)
            at util/scripting-engines/trace-event-python.c:1044
        #6  0x00005555555c5db8 in process_sample_event (tool=<optimized out>, event=<optimized out>, sample=<optimized out>,
            evsel=0x555555efc370, machine=0x555555ef4d68) at builtin-script.c:2421
        #7  0x00005555556b7793 in perf_session__deliver_event (session=0x555555ef4b60, event=0x7ffff62ff7d0, tool=0x7fffffffc150,
            file_offset=30672, file_path=0x555555efb8a0 "perf.data") at util/session.c:1639
        #8  0x00005555556bc864 in do_flush (show_progress=true, oe=0x555555efb700) at util/ordered-events.c:245
        #9  __ordered_events__flush (oe=oe@entry=0x555555efb700, how=how@entry=OE_FLUSH__FINAL, timestamp=timestamp@entry=0)
            at util/ordered-events.c:324
        #10 0x00005555556bd06e in ordered_events__flush (oe=oe@entry=0x555555efb700, how=how@entry=OE_FLUSH__FINAL)
            at util/ordered-events.c:342
        #11 0x00005555556b9d63 in __perf_session__process_events (session=0x555555ef4b60) at util/session.c:2465
        #12 perf_session__process_events (session=0x555555ef4b60) at util/session.c:2627
        #13 0x00005555555cb1d0 in __cmd_script (script=0x7fffffffc150) at builtin-script.c:2839
        #14 cmd_script (argc=<optimized out>, argv=<optimized out>) at builtin-script.c:4365
        #15 0x0000555555650811 in run_builtin (p=p@entry=0x555555ed8948 <commands+456>, argc=argc@entry=4, argv=argv@entry=0x7fffffffe240)
            at perf.c:323
        #16 0x0000555555597eb3 in handle_internal_command (argv=0x7fffffffe240, argc=4) at perf.c:377
        #17 run_argv (argv=<synthetic pointer>, argcp=<synthetic pointer>) at perf.c:421
        #18 main (argc=4, argv=0x7fffffffe240) at perf.c:537
      
      Fixes: 51cfe7a3 ("perf python: Avoid 2 leak sanitizer issues")
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Adrian Hunter <adrian.hunter@intel.com>
      Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
      Cc: Jiri Olsa <jolsa@kernel.org>
      Cc: Ingo Molnar <mingo@kernel.org>
      Acked-by: default avatarIan Rogers <irogers@google.com>
      Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
      2d7f5540
    • James Clark's avatar
      perf tests: Fix test_arm_callgraph_fp variable expansion · 33fe7c08
      James Clark authored
      $TEST_PROGRAM is a command with spaces so it's supposed to be word
      split. The referenced fix to fix the shellcheck warnings incorrectly
      quoted this string so unquote it to fix the test.
      
      At the same time silence the shellcheck warning for that line and fix
      two more shellcheck errors at the end of the script.
      
      Fixes: 1bb17b4c ("perf tests arm_callgraph_fp: Address shellcheck warnings about signal names and adding double quotes for expression")
      Signed-off-by: default avatarJames Clark <james.clark@arm.com>
      Acked-by: default avatarNamhyung Kim <namhyung@kernel.org>
      Cc: Mark Rutland <mark.rutland@arm.com>
      Cc: Ian Rogers <irogers@google.com>
      Cc: spoorts2@in.ibm.com
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Adrian Hunter <adrian.hunter@intel.com>
      Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
      Cc: Jiri Olsa <jolsa@kernel.org>
      Cc: Kajol Jain <kjain@linux.ibm.com>
      Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
      Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Link: https://lore.kernel.org/r/20230622101809.2431897-1-james.clark@arm.comSigned-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
      33fe7c08
  3. 22 Jun, 2023 5 commits
  4. 21 Jun, 2023 4 commits
    • elisabeth's avatar
      perf jit: Fix incorrect file name in DWARF line table · 362f9c90
      elisabeth authored
      Fixes an issue where an incorrect filename was added in the DWARF line table of
      an ELF object file when calling 'perf inject --jit' due to not checking the
      filename of a debug entry against the repeated name marker (/xff/0).
      The marker is mentioned in the tools/perf/util/jitdump.h header, which describes
      the jitdump binary format, and indicitates that the filename in a debug entry
      is the same as the previous enrty.
      
      In the function emit_lineno_info(), in the file tools/perf/util/genelf-debug.c,
      the debug entry filename gets compared to the previous entry filename. If they
      are not the same, a new filename is added to the DWARF line table. However,
      since there is no check against '\xff\0', in some cases '\xff\0' is inserted
      as the filename into the DWARF line table.
      
      This can be seen with `objdump --dwarf=line` on the ELF file after `perf inject --jit`.
      It also makes no source code information show up in 'perf annotate'.
      Signed-off-by: default avatarElisabeth Panholzer <elisabeth@leaningtech.com>
      Acked-by: default avatarNamhyung Kim <namhyung@kernel.org>
      Link: https://lore.kernel.org/r/20230602123815.255001-1-paniii94@gmail.com
      [ Fixed a trailing white space, removed a subject prefix ]
      Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
      362f9c90
    • WANG Rui's avatar
      perf annotate: Fix instruction association and parsing for LoongArch · 4ca0d340
      WANG Rui authored
      In the perf annotate view for LoongArch, there is no arrowed line
      pointing to the target from the branch instruction. This issue is
      caused by incorrect instruction association and parsing.
      
      $ perf record alloc-6276705c94ad1398 # rust benchmark
      $ perf report
      
        0.28 │       ori        $a1, $zero, 0x63
             │       move       $a2, $zero
       10.55 │       addi.d     $a3, $a2, 1(0x1)
             │       sltu       $a4, $a3, $s7
        9.53 │       masknez    $a4, $s7, $a4
             │       sub.d      $a3, $a3, $a4
       12.12 │       st.d       $a1, $fp, 24(0x18)
             │       st.d       $a3, $fp, 16(0x10)
       16.29 │       slli.d     $a2, $a2, 0x2
             │       ldx.w      $a2, $s8, $a2
       12.77 │       st.w       $a2, $sp, 724(0x2d4)
             │       st.w       $s0, $sp, 720(0x2d0)
        7.03 │       addi.d     $a2, $sp, 720(0x2d0)
             │       addi.d     $a1, $a1, -1(0xfff)
       12.03 │       move       $a2, $a3
             │     → bne        $a1, $s3, -52(0x3ffcc)  # 82ce8 <test::bench::Bencher::iter+0x3f4>
        2.50 │       addi.d     $a0, $a0, 1(0x1)
      
      This patch fixes instruction association issues, such as associating
      branch instructions with jump_ops instead of call_ops, and corrects
      false instruction matches. It also implements branch instruction parsing
      specifically for LoongArch. With this patch, we will be able to see the
      arrowed line.
      
        0.79 │3ec:   ori        $a1, $zero, 0x63
             │       move       $a2, $zero
       10.32 │3f4:┌─→addi.d     $a3, $a2, 1(0x1)
             │    │  sltu       $a4, $a3, $s7
       10.44 │    │  masknez    $a4, $s7, $a4
             │    │  sub.d      $a3, $a3, $a4
       14.17 │    │  st.d       $a1, $fp, 24(0x18)
             │    │  st.d       $a3, $fp, 16(0x10)
       13.15 │    │  slli.d     $a2, $a2, 0x2
             │    │  ldx.w      $a2, $s8, $a2
       11.00 │    │  st.w       $a2, $sp, 724(0x2d4)
             │    │  st.w       $s0, $sp, 720(0x2d0)
        8.00 │    │  addi.d     $a2, $sp, 720(0x2d0)
             │    │  addi.d     $a1, $a1, -1(0xfff)
       11.99 │    │  move       $a2, $a3
             │    └──bne        $a1, $s3, 3f4
        3.17 │       addi.d     $a0, $a0, 1(0x1)
      Signed-off-by: default avatarWANG Rui <wangrui@loongson.cn>
      Acked-by: default avatarNamhyung Kim <namhyung@kernel.org>
      Cc: Mark Rutland <mark.rutland@arm.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
      Cc: Jiri Olsa <jolsa@kernel.org>
      Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
      Cc: loongarch@lists.linux.dev
      Cc: loongson-kernel@lists.loongnix.cn
      Cc: Huacai Chen <chenhuacai@loongson.cn>
      Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: WANG Xuerui <kernel@xen0n.name>
      Link: https://lore.kernel.org/r/20230620132025.105563-1-wangrui@loongson.cnSigned-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
      4ca0d340
    • Ian Rogers's avatar
      perf annotation: Switch lock from a mutex to a sharded_mutex · 2e9f9d4a
      Ian Rogers authored
      Remove the "struct mutex lock" variable from annotation that is
      allocated per symbol. This removes in the region of 40 bytes per
      symbol allocation. Use a sharded mutex where the number of shards is
      set to the number of CPUs. Assuming good hashing of the annotation
      (done based on the pointer), this means in order to contend there
      needs to be more threads than CPUs, which is not currently true in any
      perf command. Were contention an issue it is straightforward to
      increase the number of shards in the mutex.
      
      On my Debian/glibc based machine, this reduces the size of struct
      annotation from 136 bytes to 96 bytes, or nearly 30%.
      Signed-off-by: default avatarIan Rogers <irogers@google.com>
      Acked-by: default avatarNamhyung Kim <namhyung@kernel.org>
      Cc: Andres Freund <andres@anarazel.de>
      Cc: Mark Rutland <mark.rutland@arm.com>
      Cc: Yuan Can <yuancan@huawei.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Adrian Hunter <adrian.hunter@intel.com>
      Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
      Cc: Huacai Chen <chenhuacai@kernel.org>
      Cc: Jiri Olsa <jolsa@kernel.org>
      Cc: Masami Hiramatsu <mhiramat@kernel.org>
      Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
      Cc: Kan Liang <kan.liang@linux.intel.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Link: https://lore.kernel.org/r/20230615040715.2064350-2-irogers@google.comSigned-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
      2e9f9d4a
    • Ian Rogers's avatar
      perf sharded_mutex: Introduce sharded_mutex · 0650b2b2
      Ian Rogers authored
      Per object mutexes may come with significant memory cost while a
      global mutex can suffer from unnecessary contention. A sharded mutex
      is a compromise where objects are hashed and then a particular mutex
      for the hash of the object used. Contention can be controlled by the
      number of shards.
      
      v2. Use hashmap.h's hash_bits in case of contention from alignment of
          objects.
      Signed-off-by: default avatarIan Rogers <irogers@google.com>
      Acked-by: default avatarNamhyung Kim <namhyung@kernel.org>
      Cc: Andres Freund <andres@anarazel.de>
      Cc: Mark Rutland <mark.rutland@arm.com>
      Cc: Yuan Can <yuancan@huawei.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Adrian Hunter <adrian.hunter@intel.com>
      Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
      Cc: Huacai Chen <chenhuacai@kernel.org>
      Cc: Jiri Olsa <jolsa@kernel.org>
      Cc: Masami Hiramatsu <mhiramat@kernel.org>
      Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
      Cc: Kan Liang <kan.liang@linux.intel.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Link: https://lore.kernel.org/r/20230615040715.2064350-1-irogers@google.comSigned-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
      0650b2b2
  5. 20 Jun, 2023 5 commits
  6. 16 Jun, 2023 18 commits