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OpenCloudOS-Kernel
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Author SHA1 Message Date
Kajol Jain 9823ae6f68 perf bench breakpoint: Skip run if no breakpoints available 
Based on commit 7d54a4acd8 ("perf test: Skip watchpoint tests if
no watchpoints available"), hardware breakpoints are not available for
power9 platform and because of that 'perf bench breakpoint' run fails on
power9 platform.

Add code to check for the return value of perf_event_open() in the
breakpoint run and skip the 'perf bench breakpoint' run, if hardware
breakpoints are not available.

Result on power9 system before patch changes:

  [command]# perf bench breakpoint thread
  perf_event_open: No such device

Result on power9 system after patch changes:

  [command]# ./perf bench breakpoint thread
  Skipping perf bench breakpoint thread: No hardware support

Reported-by: Disha Goel <disgoel@linux.vnet.ibm.com>
Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Acked-by: Naveen N Rao <naveen@kernel.org>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Disha Goel <disgoel@linux.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20230823075103.190565-1-kjain@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
 2023-08-23 08:39:02 -03:00
Arnaldo Carvalho de Melo df36d2572e perf bench breakpoint: Fix build on 32-bit arches 
Cast pointers to unsigned long instead of to uint64_t to avoid this
problem on 32-bit arches:

  31     6.89 debian:experimental-x-mips    : FAIL gcc version 11.2.0 (Debian 11.2.0-18)
    bench/breakpoint.c: In function 'breakpoint_setup':
    bench/breakpoint.c:56:24: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
       56 |         attr.bp_addr = (uint64_t)addr;
          |                        ^
    cc1: all warnings being treated as errors
    make[3]: *** [/git/perf-5.18.0-rc7/tools/build/Makefile.build:139: bench] Error 2

Fixes: 68a6772f11 ("perf bench: Add breakpoint benchmarks")
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Marco Elver <elver@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/YoLq1nHx1doi+VWl@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
 2022-05-16 21:23:09 -03:00
Dmitry Vyukov 68a6772f11 perf bench: Add breakpoint benchmarks 
Add 2 benchmarks:

1. Performance of thread creation/exiting in presence of breakpoints.
2. Performance of breakpoint modification in presence of threads.

The benchmarks capture use cases that we are interested in:
using inheritable breakpoints in large highly-threaded applications.

The benchmarks show significant slowdown imposed by breakpoints
(even when they don't fire).

Testing on Intel 8173M with 112 HW threads show:

  perf bench --repeat=56 breakpoint thread --breakpoints=0 --parallelism=56 --threads=20
        78.675000 usecs/op
  perf bench --repeat=56 breakpoint thread --breakpoints=4 --parallelism=56 --threads=20
     12967.135714 usecs/op

That's 165x slowdown due to presence of the breakpoints.

  perf bench --repeat=20000 breakpoint enable --passive=0 --active=0
         1.433250 usecs/op
  perf bench --repeat=20000 breakpoint enable --passive=224 --active=0
       585.318400 usecs/op
  perf bench --repeat=20000 breakpoint enable --passive=0 --active=111
       635.953000 usecs/op

That's 408x and 444x slowdown due to presence of threads.

Profiles show some overhead in toggle_bp_slot,
but also very high contention:

    90.83%  breakpoint-thre  [kernel.kallsyms]  [k] osq_lock
     4.69%  breakpoint-thre  [kernel.kallsyms]  [k] mutex_spin_on_owner
     2.06%  breakpoint-thre  [kernel.kallsyms]  [k] __reserve_bp_slot
     2.04%  breakpoint-thre  [kernel.kallsyms]  [k] toggle_bp_slot

    79.01%  breakpoint-enab  [kernel.kallsyms]  [k] smp_call_function_single
     9.94%  breakpoint-enab  [kernel.kallsyms]  [k] llist_add_batch
     5.70%  breakpoint-enab  [kernel.kallsyms]  [k] _raw_spin_lock_irq
     1.84%  breakpoint-enab  [kernel.kallsyms]  [k] event_function_call
     1.12%  breakpoint-enab  [kernel.kallsyms]  [k] send_call_function_single_ipi
     0.37%  breakpoint-enab  [kernel.kallsyms]  [k] generic_exec_single
     0.24%  breakpoint-enab  [kernel.kallsyms]  [k] __perf_event_disable
     0.20%  breakpoint-enab  [kernel.kallsyms]  [k] _perf_event_enable
     0.18%  breakpoint-enab  [kernel.kallsyms]  [k] toggle_bp_slot

Committer notes:

Fixup struct init for older compilers:

   3    32.90 alpine:3.5                    : FAIL clang version 3.8.1 (tags/RELEASE_381/final)
    bench/breakpoint.c:49:34: error: missing field 'size' initializer [-Werror,-Wmissing-field-initializers]
            struct perf_event_attr attr = {0};
                                            ^
    1 error generated.
   7    37.31 alpine:3.9                    : FAIL gcc version 8.3.0 (Alpine 8.3.0)
    bench/breakpoint.c:49:34: error: missing field 'size' initializer [-Werror,-Wmissing-field-initializers]
            struct perf_event_attr attr = {0};
                                            ^
    1 error generated.

Signed-off-by: Dmitriy Vyukov <dvyukov@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Marco Elver <elver@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220505155745.1690906-1-dvyukov@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
 2022-05-13 11:00:38 -03:00