Messages in this thread | | | Date | Fri, 11 Sep 2015 19:50:54 +0800 | From | "Wangnan (F)" <> | Subject | Re: [PATCH 10/13] perf report: Do not blindly use env->cpu[al.cpu].socket_id |
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On 2015/9/10 3:50, Arnaldo Carvalho de Melo wrote: > From: Arnaldo Carvalho de Melo <acme@redhat.com> > > As al.cpu may be -1, i.e. no PERF_SAMPLE_CPU, and env->cpu may be NULL. > > Rely instead on the work now done in perf_event__preprocess_sample(), > that does all those checks. > > Reported-by: Wang Nan <wangnan0@huawei.com> > Based-on-a-patch-by: Jiri Olsa <jolsa@kernel.org> > Cc: Adrian Hunter <adrian.hunter@intel.com> > Cc: Borislav Petkov <bp@suse.de> > Cc: David Ahern <dsahern@gmail.com> > Cc: Frederic Weisbecker <fweisbec@gmail.com> > Cc: Kan Liang <kan.liang@intel.com> > Cc: Namhyung Kim <namhyung@kernel.org> > Cc: Stephane Eranian <eranian@google.com> > Cc: Wang Nan <wangnan0@huawei.com> > Link: http://lkml.kernel.org/n/tip-2lw80g5ehsrec7tozhmnjgxw@git.kernel.org > Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> > --- > tools/perf/builtin-report.c | 4 ---- > 1 file changed, 4 deletions(-) > > diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c > index 4b432453922f..9b5083630a56 100644 > --- a/tools/perf/builtin-report.c > +++ b/tools/perf/builtin-report.c > @@ -150,7 +150,6 @@ static int process_sample_event(struct perf_tool *tool, > .add_entry_cb = hist_iter__report_callback, > }; > int ret = 0; > - struct perf_env *env = evsel->evlist->env; > > if (perf_event__preprocess_sample(event, machine, &al, sample) < 0) { > pr_debug("problem processing %d event, skipping it.\n", > @@ -158,9 +157,6 @@ static int process_sample_event(struct perf_tool *tool, > return -1; > } > > - /* read socket id from perf.data for perf report */ > - al.socket = env->cpu[al.cpu].socket_id; > - > if (rep->hide_unresolved && al.sym == NULL) > goto out_put; >
I tested this patch on an 8 cores SOC. No segfault found now.
Normal case:
# ./perf record -a ls # ... # ./perf_arm64 report -v --stdio -s socket,cpu build id event received for [kernel.kallsyms]: ... # To display the perf.data header info, please use --header/--header-only options. # symsrc__init: cannot get elf header. Looking at the vmlinux_path (7 entries long) Failed to open /proc/kcore. Note /proc/kcore requires CAP_SYS_RAWIO capability to access. Using /proc/kallsyms for symbols Failed to open /sbin/adbd, continuing without symbols # # Total Lost Samples: 0 # # Samples: 291 of event 'cycles' # Event count (approx.): 40968659 # # Overhead Socket CPU # ........ ...... ... # 58.01% 000 004 35.61% 000 007 3.65% 000 005 1.23% 001 000 1.18% 001 001 0.19% 000 006 0.08% 001 002 0.07% 001 003
If one of CPUs is offlined before 'perf record':
# ./perf record -a ls # ... # ./perf_arm64 report -v --stdio -s socket,cpu build id event received for [kernel.kallsyms]: d287ff3393fb1a01d3a785c3a1dac6e63d973bce # To display the perf.data header info, please use --header/--header-only options. # symsrc__init: cannot get elf header. Looking at the vmlinux_path (7 entries long) Failed to open /proc/kcore. Note /proc/kcore requires CAP_SYS_RAWIO capability to access. Using /proc/kallsyms for symbols Failed to open /sbin/adbd, continuing without symbols # # Total Lost Samples: 0 # # Samples: 304 of event 'cycles' # Event count (approx.): 42027298 # # Overhead Socket CPU # ........ ...... ... # 60.25% -001 004 32.69% -001 007 5.00% -001 005 1.34% -001 003 0.37% -001 000 0.20% -001 006 0.08% -001 002 0.07% -001 001
And if CPU is offlined during perf record (between build_cpu_topology() and perf_env__read_cpu_topology_map()):
# ./perf report -v --stdio -s socket,cpu build id event received for [kernel.kallsyms]: ... core_id number is too big.You may need to upgrade the perf tool. <--- *please see this line* # To display the perf.data header info, please use --header/--header-only options. # symsrc__init: cannot get elf header. Looking at the vmlinux_path (7 entries long) Failed to open /proc/kcore. Note /proc/kcore requires CAP_SYS_RAWIO capability to access. Using /proc/kallsyms for symbols # # Total Lost Samples: 0 # # Samples: 278 of event 'cycles' # Event count (approx.): 37729429 # # Overhead Socket CPU # ........ ...... ... # 59.06% -001 004 36.93% -001 007 1.33% -001 000 1.18% -001 005 0.82% -001 006 0.50% -001 001 0.08% -001 002 0.08% -001 003
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