* [PATCH 1/1] perf,stat: reduce interval-print to 10ms
@ 2015-10-02 9:04 kan.liang
2015-10-02 16:56 ` Jiri Olsa
2015-10-03 7:51 ` [tip:perf/core] perf stat: Reduce min --interval-print " tip-bot for Kan Liang
0 siblings, 2 replies; 7+ messages in thread
From: kan.liang @ 2015-10-02 9:04 UTC (permalink / raw)
To: acme; +Cc: jolsa, namhyung, ak, linux-kernel, Kan Liang
From: Kan Liang <kan.liang@intel.com>
The interval-print used to be limited to 100ms. However, for example,
10ms is required to do sophisticated bandwidth analysis using uncore
event.
The test shows that the overhead of the system-wide uncore monitoring
with 10ms interval is only ~2%. So this patch reduces interval-print to
10ms.
But 10ms may not work well for all cases. For example, when the
cpus/threads number is very large, for system-wide core event monitoring
the overhead could be high. To handle this issue, a warning will be
displayed when the interval-print is set between 10ms to 100ms. So the
users can make a decision according to their specific cases.
#perf stat -e uncore_imc_1/cas_count_read/ -a --interval-print 10 --
sleep 1
print interval < 100ms. The overhead percentage could be high in some
cases. Please proceed with caution.
# time counts unit events
0.010200451 0.10 MiB uncore_imc_1/cas_count_read/
0.020475117 0.02 MiB uncore_imc_1/cas_count_read/
0.030692800 0.01 MiB uncore_imc_1/cas_count_read/
0.040948161 0.02 MiB uncore_imc_1/cas_count_read/
0.051159564 0.00 MiB uncore_imc_1/cas_count_read/
Signed-off-by: Kan Liang <kan.liang@intel.com>
---
tools/perf/Documentation/perf-stat.txt | 2 +-
tools/perf/builtin-stat.c | 13 +++++++++----
2 files changed, 10 insertions(+), 5 deletions(-)
diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
index 47469ab..7586fe0 100644
--- a/tools/perf/Documentation/perf-stat.txt
+++ b/tools/perf/Documentation/perf-stat.txt
@@ -128,7 +128,7 @@ perf stat --repeat 10 --null --sync --pre 'make -s O=defconfig-build/clean' -- m
-I msecs::
--interval-print msecs::
- Print count deltas every N milliseconds (minimum: 100ms)
+ Print count deltas every N milliseconds (minimum: 10ms)
example: perf stat -I 1000 -e cycles -a sleep 5
--per-socket::
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index a96fb5c..5ef88f7 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -1179,7 +1179,7 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused)
OPT_STRING(0, "post", &post_cmd, "command",
"command to run after to the measured command"),
OPT_UINTEGER('I', "interval-print", &stat_config.interval,
- "print counts at regular interval in ms (>= 100)"),
+ "print counts at regular interval in ms (>= 10)"),
OPT_SET_UINT(0, "per-socket", &stat_config.aggr_mode,
"aggregate counts per processor socket", AGGR_SOCKET),
OPT_SET_UINT(0, "per-core", &stat_config.aggr_mode,
@@ -1332,9 +1332,14 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused)
thread_map__read_comms(evsel_list->threads);
if (interval && interval < 100) {
- pr_err("print interval must be >= 100ms\n");
- parse_options_usage(stat_usage, options, "I", 1);
- goto out;
+ if (interval < 10) {
+ pr_err("print interval must be >= 10ms\n");
+ parse_options_usage(stat_usage, options, "I", 1);
+ goto out;
+ } else
+ pr_warning("print interval < 100ms. "
+ "The overhead percentage could be high in some cases. "
+ "Please proceed with caution.\n");
}
if (perf_evlist__alloc_stats(evsel_list, interval))
--
1.8.3.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH 1/1] perf,stat: reduce interval-print to 10ms
2015-10-02 9:04 [PATCH 1/1] perf,stat: reduce interval-print to 10ms kan.liang
@ 2015-10-02 16:56 ` Jiri Olsa
2015-10-02 20:08 ` Arnaldo Carvalho de Melo
2015-10-03 7:51 ` [tip:perf/core] perf stat: Reduce min --interval-print " tip-bot for Kan Liang
1 sibling, 1 reply; 7+ messages in thread
From: Jiri Olsa @ 2015-10-02 16:56 UTC (permalink / raw)
To: kan.liang; +Cc: acme, jolsa, namhyung, ak, linux-kernel, Stephane Eranian
On Fri, Oct 02, 2015 at 05:04:34AM -0400, kan.liang@intel.com wrote:
> From: Kan Liang <kan.liang@intel.com>
>
SNIP
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index a96fb5c..5ef88f7 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -1179,7 +1179,7 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused)
> OPT_STRING(0, "post", &post_cmd, "command",
> "command to run after to the measured command"),
> OPT_UINTEGER('I', "interval-print", &stat_config.interval,
> - "print counts at regular interval in ms (>= 100)"),
> + "print counts at regular interval in ms (>= 10)"),
> OPT_SET_UINT(0, "per-socket", &stat_config.aggr_mode,
> "aggregate counts per processor socket", AGGR_SOCKET),
> OPT_SET_UINT(0, "per-core", &stat_config.aggr_mode,
> @@ -1332,9 +1332,14 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused)
> thread_map__read_comms(evsel_list->threads);
>
> if (interval && interval < 100) {
> - pr_err("print interval must be >= 100ms\n");
> - parse_options_usage(stat_usage, options, "I", 1);
> - goto out;
> + if (interval < 10) {
> + pr_err("print interval must be >= 10ms\n");
> + parse_options_usage(stat_usage, options, "I", 1);
> + goto out;
> + } else
> + pr_warning("print interval < 100ms. "
> + "The overhead percentage could be high in some cases. "
> + "Please proceed with caution.\n");
with '-I' 10 this warning flies away quite fast ;-)
I guess it's better than nothing, and I'm not sure
about putting some sleep after that warning..
Acked-by: Jiri Olsa <jolsa@kernel.org>
thanks,
jirka
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 1/1] perf,stat: reduce interval-print to 10ms
2015-10-02 16:56 ` Jiri Olsa
@ 2015-10-02 20:08 ` Arnaldo Carvalho de Melo
2015-10-02 20:22 ` Liang, Kan
0 siblings, 1 reply; 7+ messages in thread
From: Arnaldo Carvalho de Melo @ 2015-10-02 20:08 UTC (permalink / raw)
To: Jiri Olsa; +Cc: kan.liang, jolsa, namhyung, ak, linux-kernel, Stephane Eranian
Em Fri, Oct 02, 2015 at 06:56:24PM +0200, Jiri Olsa escreveu:
> On Fri, Oct 02, 2015 at 05:04:34AM -0400, kan.liang@intel.com wrote:
> > From: Kan Liang <kan.liang@intel.com>
> >
>
> SNIP
>
> > diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> > index a96fb5c..5ef88f7 100644
> > --- a/tools/perf/builtin-stat.c
> > +++ b/tools/perf/builtin-stat.c
> > @@ -1179,7 +1179,7 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused)
> > OPT_STRING(0, "post", &post_cmd, "command",
> > "command to run after to the measured command"),
> > OPT_UINTEGER('I', "interval-print", &stat_config.interval,
> > - "print counts at regular interval in ms (>= 100)"),
> > + "print counts at regular interval in ms (>= 10)"),
> > OPT_SET_UINT(0, "per-socket", &stat_config.aggr_mode,
> > "aggregate counts per processor socket", AGGR_SOCKET),
> > OPT_SET_UINT(0, "per-core", &stat_config.aggr_mode,
> > @@ -1332,9 +1332,14 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused)
> > thread_map__read_comms(evsel_list->threads);
> >
> > if (interval && interval < 100) {
> > - pr_err("print interval must be >= 100ms\n");
> > - parse_options_usage(stat_usage, options, "I", 1);
> > - goto out;
> > + if (interval < 10) {
> > + pr_err("print interval must be >= 10ms\n");
> > + parse_options_usage(stat_usage, options, "I", 1);
> > + goto out;
> > + } else
> > + pr_warning("print interval < 100ms. "
> > + "The overhead percentage could be high in some cases. "
> > + "Please proceed with caution.\n");
>
> with '-I' 10 this warning flies away quite fast ;-)
>
> I guess it's better than nothing, and I'm not sure
> about putting some sleep after that warning..
>
> Acked-by: Jiri Olsa <jolsa@kernel.org>
Right, this should appear in the man page as well, I added the patch
below, we could also print that warning when the workload ends.
- Arnaldo
diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
index 7586fe08ac9a..641caf66ff26 100644
--- a/tools/perf/Documentation/perf-stat.txt
+++ b/tools/perf/Documentation/perf-stat.txt
@@ -130,6 +130,8 @@ perf stat --repeat 10 --null --sync --pre 'make -s O=defconfig-build/clean' -- m
--interval-print msecs::
Print count deltas every N milliseconds (minimum: 10ms)
example: perf stat -I 1000 -e cycles -a sleep 5
+ The overhead percentage could be high in some cases, for instance
+ with small, sub 100ms intervals. Use with caution.
--per-socket::
Aggregate counts per processor socket for system-wide mode measurements. This
^ permalink raw reply related [flat|nested] 7+ messages in thread
* RE: [PATCH 1/1] perf,stat: reduce interval-print to 10ms
2015-10-02 20:08 ` Arnaldo Carvalho de Melo
@ 2015-10-02 20:22 ` Liang, Kan
2015-10-02 20:40 ` Arnaldo Carvalho de Melo
0 siblings, 1 reply; 7+ messages in thread
From: Liang, Kan @ 2015-10-02 20:22 UTC (permalink / raw)
To: Arnaldo Carvalho de Melo, Jiri Olsa
Cc: jolsa, namhyung, ak, linux-kernel, Stephane Eranian
> > SNIP
> >
> > > diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> > > index a96fb5c..5ef88f7 100644
> > > --- a/tools/perf/builtin-stat.c
> > > +++ b/tools/perf/builtin-stat.c
> > > @@ -1179,7 +1179,7 @@ int cmd_stat(int argc, const char **argv, const
> char *prefix __maybe_unused)
> > > OPT_STRING(0, "post", &post_cmd, "command",
> > > "command to run after to the measured
> command"),
> > > OPT_UINTEGER('I', "interval-print", &stat_config.interval,
> > > - "print counts at regular interval in ms (>= 100)"),
> > > + "print counts at regular interval in ms (>= 10)"),
> > > OPT_SET_UINT(0, "per-socket", &stat_config.aggr_mode,
> > > "aggregate counts per processor socket",
> AGGR_SOCKET),
> > > OPT_SET_UINT(0, "per-core", &stat_config.aggr_mode, @@ -
> 1332,9
> > > +1332,14 @@ int cmd_stat(int argc, const char **argv, const char
> *prefix __maybe_unused)
> > > thread_map__read_comms(evsel_list->threads);
> > >
> > > if (interval && interval < 100) {
> > > - pr_err("print interval must be >= 100ms\n");
> > > - parse_options_usage(stat_usage, options, "I", 1);
> > > - goto out;
> > > + if (interval < 10) {
> > > + pr_err("print interval must be >= 10ms\n");
> > > + parse_options_usage(stat_usage, options, "I", 1);
> > > + goto out;
> > > + } else
> > > + pr_warning("print interval < 100ms. "
> > > + "The overhead percentage could be high
> in some cases. "
> > > + "Please proceed with caution.\n");
> >
> > with '-I' 10 this warning flies away quite fast ;-)
> >
> > I guess it's better than nothing, and I'm not sure about putting some
> > sleep after that warning..
> >
> > Acked-by: Jiri Olsa <jolsa@kernel.org>
>
> Right, this should appear in the man page as well, I added the patch below,
> we could also print that warning when the workload ends.
>
OK. We can print the warning message again at the end as the patch below.
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 5ef88f7..01209c7 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -1377,6 +1377,11 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused)
if (!forever && status != -1 && !interval)
print_counters(NULL, argc, argv);
+ if (interval && interval < 100)
+ pr_warning("print interval < 100ms. "
+ "The overhead percentage could be high in some cases. "
+ "Please proceed with caution.\n");
+
perf_evlist__free_stats(evsel_list);
out:
perf_evlist__delete(evsel_list);
Thanks,
Kan
> - Arnaldo
>
> diff --git a/tools/perf/Documentation/perf-stat.txt
> b/tools/perf/Documentation/perf-stat.txt
> index 7586fe08ac9a..641caf66ff26 100644
> --- a/tools/perf/Documentation/perf-stat.txt
> +++ b/tools/perf/Documentation/perf-stat.txt
> @@ -130,6 +130,8 @@ perf stat --repeat 10 --null --sync --pre 'make -s
> O=defconfig-build/clean' -- m --interval-print msecs::
> Print count deltas every N milliseconds (minimum: 10ms)
> example: perf stat -I 1000 -e cycles -a sleep 5
> + The overhead percentage could be high in some cases, for instance
> + with small, sub 100ms intervals. Use with caution.
>
> --per-socket::
> Aggregate counts per processor socket for system-wide mode
> measurements. This
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH 1/1] perf,stat: reduce interval-print to 10ms
2015-10-02 20:22 ` Liang, Kan
@ 2015-10-02 20:40 ` Arnaldo Carvalho de Melo
2015-10-02 20:50 ` Liang, Kan
0 siblings, 1 reply; 7+ messages in thread
From: Arnaldo Carvalho de Melo @ 2015-10-02 20:40 UTC (permalink / raw)
To: Liang, Kan; +Cc: Jiri Olsa, jolsa, namhyung, ak, linux-kernel, Stephane Eranian
Em Fri, Oct 02, 2015 at 08:22:06PM +0000, Liang, Kan escreveu:
> > > > + if (interval < 10) {
> > > > + pr_err("print interval must be >= 10ms\n");
> > > > + parse_options_usage(stat_usage, options, "I", 1);
> > > > + goto out;
> > > > + } else
> > > > + pr_warning("print interval < 100ms. "
> > > > + "The overhead percentage could be high
> > in some cases. "
> > > > + "Please proceed with caution.\n");
> > >
> > > with '-I' 10 this warning flies away quite fast ;-)
> > >
> > > I guess it's better than nothing, and I'm not sure about putting some
> > > sleep after that warning..
> > >
> > > Acked-by: Jiri Olsa <jolsa@kernel.org>
> >
> > Right, this should appear in the man page as well, I added the patch below,
> > we could also print that warning when the workload ends.
> OK. We can print the warning message again at the end as the patch below.
>
> +++ b/tools/perf/builtin-stat.c
> @@ -1377,6 +1377,11 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused)
> if (!forever && status != -1 && !interval)
> print_counters(NULL, argc, argv);
>
> + if (interval && interval < 100)
> + pr_warning("print interval < 100ms. "
> + "The overhead percentage could be high in some cases. "
> + "Please proceed with caution.\n");
Yeah, something like that, but the warning then becomes strange,
"proceed"? I guess that something like:
pr_warning("print interval < 100ms. "
"The overhead percentage could have been high. "
"Take that into account when interpreting the these numbers.\n");
Right?
- Arnaldo
> +
> perf_evlist__free_stats(evsel_list);
> out:
> perf_evlist__delete(evsel_list);
^ permalink raw reply [flat|nested] 7+ messages in thread
* RE: [PATCH 1/1] perf,stat: reduce interval-print to 10ms
2015-10-02 20:40 ` Arnaldo Carvalho de Melo
@ 2015-10-02 20:50 ` Liang, Kan
0 siblings, 0 replies; 7+ messages in thread
From: Liang, Kan @ 2015-10-02 20:50 UTC (permalink / raw)
To: Arnaldo Carvalho de Melo
Cc: Jiri Olsa, jolsa, namhyung, ak, linux-kernel, Stephane Eranian
> -----Original Message-----
> From: Arnaldo Carvalho de Melo [mailto:acme@kernel.org]
> Sent: Friday, October 02, 2015 4:40 PM
> To: Liang, Kan
> Cc: Jiri Olsa; jolsa@kernel.org; namhyung@kernel.org; ak@linux.intel.com;
> linux-kernel@vger.kernel.org; Stephane Eranian
> Subject: Re: [PATCH 1/1] perf,stat: reduce interval-print to 10ms
>
> Em Fri, Oct 02, 2015 at 08:22:06PM +0000, Liang, Kan escreveu:
> > > > > + if (interval < 10) {
> > > > > + pr_err("print interval must be >= 10ms\n");
> > > > > + parse_options_usage(stat_usage, options,
> "I", 1);
> > > > > + goto out;
> > > > > + } else
> > > > > + pr_warning("print interval < 100ms. "
> > > > > + "The overhead percentage could
> be high
> > > in some cases. "
> > > > > + "Please proceed with caution.\n");
> > > >
> > > > with '-I' 10 this warning flies away quite fast ;-)
> > > >
> > > > I guess it's better than nothing, and I'm not sure about putting
> > > > some sleep after that warning..
> > > >
> > > > Acked-by: Jiri Olsa <jolsa@kernel.org>
> > >
> > > Right, this should appear in the man page as well, I added the patch
> > > below, we could also print that warning when the workload ends.
>
> > OK. We can print the warning message again at the end as the patch
> below.
> >
> > +++ b/tools/perf/builtin-stat.c
> > @@ -1377,6 +1377,11 @@ int cmd_stat(int argc, const char **argv, const
> char *prefix __maybe_unused)
> > if (!forever && status != -1 && !interval)
> > print_counters(NULL, argc, argv);
> >
> > + if (interval && interval < 100)
> > + pr_warning("print interval < 100ms. "
> > + "The overhead percentage could be high in some
> cases. "
> > + "Please proceed with caution.\n");
>
> Yeah, something like that, but the warning then becomes strange,
> "proceed"? I guess that something like:
>
> pr_warning("print interval < 100ms. "
> "The overhead percentage could have been high.
> "
> "Take that into account when interpreting the
> these numbers.\n");
>
> Right?
Yes.
Thanks,
Kan
>
> - Arnaldo
>
> > +
> > perf_evlist__free_stats(evsel_list);
> > out:
> > perf_evlist__delete(evsel_list);
^ permalink raw reply [flat|nested] 7+ messages in thread
* [tip:perf/core] perf stat: Reduce min --interval-print to 10ms
2015-10-02 9:04 [PATCH 1/1] perf,stat: reduce interval-print to 10ms kan.liang
2015-10-02 16:56 ` Jiri Olsa
@ 2015-10-03 7:51 ` tip-bot for Kan Liang
1 sibling, 0 replies; 7+ messages in thread
From: tip-bot for Kan Liang @ 2015-10-03 7:51 UTC (permalink / raw)
To: linux-tip-commits
Cc: tglx, acme, jolsa, namhyung, mingo, ak, kan.liang, linux-kernel, hpa
Commit-ID: 19afd10410957b1c808c2c49a88e6dd8b23aa894
Gitweb: http://git.kernel.org/tip/19afd10410957b1c808c2c49a88e6dd8b23aa894
Author: Kan Liang <kan.liang@intel.com>
AuthorDate: Fri, 2 Oct 2015 05:04:34 -0400
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Fri, 2 Oct 2015 17:07:55 -0300
perf stat: Reduce min --interval-print to 10ms
The --interval-print parameter was limited to 100ms. However, for
example, 10ms is required to do sophisticated bandwidth analysis using
uncore events.
The test shows that the overhead of the system-wide uncore monitoring
with 10ms interval is only ~2%. So this patch reduces the minimal
interval-print allowd to 10ms.
But 10ms may not work well for all cases. For example, when the
cpus/threads number is very large, for system-wide core event monitoring
the overhead could be high.
To handle this issue, a warning will be displayed when the
interval-print is set between 10ms to 100ms. So users can make a
decision according to their specific cases.
# perf stat -e uncore_imc_1/cas_count_read/ -a --interval-print 10 -- sleep 1
print interval < 100ms. The overhead percentage could be high in some
cases. Please proceed with caution.
# time counts unit events
0.010200451 0.10 MiB uncore_imc_1/cas_count_read/
0.020475117 0.02 MiB uncore_imc_1/cas_count_read/
0.030692800 0.01 MiB uncore_imc_1/cas_count_read/
0.040948161 0.02 MiB uncore_imc_1/cas_count_read/
0.051159564 0.00 MiB uncore_imc_1/cas_count_read/
Signed-off-by: Kan Liang <kan.liang@intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1443776674-42511-1-git-send-email-kan.liang@intel.com
[ Added warning about overhead when using sub 100ms intervals to the man page ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/Documentation/perf-stat.txt | 5 +++--
tools/perf/builtin-stat.c | 13 +++++++++----
2 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
index 47469ab..4e074a6 100644
--- a/tools/perf/Documentation/perf-stat.txt
+++ b/tools/perf/Documentation/perf-stat.txt
@@ -128,8 +128,9 @@ perf stat --repeat 10 --null --sync --pre 'make -s O=defconfig-build/clean' -- m
-I msecs::
--interval-print msecs::
- Print count deltas every N milliseconds (minimum: 100ms)
- example: perf stat -I 1000 -e cycles -a sleep 5
+Print count deltas every N milliseconds (minimum: 10ms)
+The overhead percentage could be high in some cases, for instance with small, sub 100ms intervals. Use with caution.
+ example: 'perf stat -I 1000 -e cycles -a sleep 5'
--per-socket::
Aggregate counts per processor socket for system-wide mode measurements. This
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index a96fb5c..5ef88f7 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -1179,7 +1179,7 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused)
OPT_STRING(0, "post", &post_cmd, "command",
"command to run after to the measured command"),
OPT_UINTEGER('I', "interval-print", &stat_config.interval,
- "print counts at regular interval in ms (>= 100)"),
+ "print counts at regular interval in ms (>= 10)"),
OPT_SET_UINT(0, "per-socket", &stat_config.aggr_mode,
"aggregate counts per processor socket", AGGR_SOCKET),
OPT_SET_UINT(0, "per-core", &stat_config.aggr_mode,
@@ -1332,9 +1332,14 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused)
thread_map__read_comms(evsel_list->threads);
if (interval && interval < 100) {
- pr_err("print interval must be >= 100ms\n");
- parse_options_usage(stat_usage, options, "I", 1);
- goto out;
+ if (interval < 10) {
+ pr_err("print interval must be >= 10ms\n");
+ parse_options_usage(stat_usage, options, "I", 1);
+ goto out;
+ } else
+ pr_warning("print interval < 100ms. "
+ "The overhead percentage could be high in some cases. "
+ "Please proceed with caution.\n");
}
if (perf_evlist__alloc_stats(evsel_list, interval))
^ permalink raw reply related [flat|nested] 7+ messages in thread
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2015-10-02 9:04 [PATCH 1/1] perf,stat: reduce interval-print to 10ms kan.liang
2015-10-02 16:56 ` Jiri Olsa
2015-10-02 20:08 ` Arnaldo Carvalho de Melo
2015-10-02 20:22 ` Liang, Kan
2015-10-02 20:40 ` Arnaldo Carvalho de Melo
2015-10-02 20:50 ` Liang, Kan
2015-10-03 7:51 ` [tip:perf/core] perf stat: Reduce min --interval-print " tip-bot for Kan Liang
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