Re: [PATCH 10/13] perf report: Do not blindly use env->cpu[al.cpu].socket_id
From: Wangnan (F)
Date: Fri Sep 11 2015 - 07:51:17 EST
On 2015/9/10 3:50, Arnaldo Carvalho de Melo wrote:
From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
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@xxxxxxxxxx>
Based-on-a-patch-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Kan Liang <kan.liang@xxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-2lw80g5ehsrec7tozhmnjgxw@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
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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