Messages in this thread | | | Date | Wed, 17 Jun 2015 14:53:02 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH V3 1/2] perf,tools: add time out to force stop proc map processing |
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Em Wed, Jun 17, 2015 at 10:05:07AM -0600, David Ahern escreveu: > On 6/17/15 1:56 AM, kan.liang@intel.com wrote: > >diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c > >index 793b150..ac6cf2a 100644 > >--- a/tools/perf/util/event.c > >+++ b/tools/perf/util/event.c > >@@ -213,6 +213,8 @@ static int perf_event__synthesize_fork(struct perf_tool *tool, > > return 0; > > }
> >+#define MMAP_TIMEOUT (50 * 1000000ULL)
> How did you determine 50msec is a good time? This seems really low to me > considering the range of platforms supported by perf and various run time > conditions. The default needs to work right on all platforms.
> Why not have the default be infinity and users who need the feature use the > option provided in patch 2?
Don't think that is a reasonable approach, how would be the workflow, something like:
1) Fire up 'perf top'
2) Wait a long time.... maybe something is wrong, I guess I better exit, press Q, no response, ok, I think I'll kill this bugger
3) Read docs, etc, ah! That is it! --proc-map-timeout! How couldn't I think of that?
8-)
I think limiting this to say, half a second is ok, and the message about the truncation happening surely suggests using --proc-map-timeout, right?
Also please rename this MMAP_TIMEOUT define, this is not about a timeout for a mmap operation, it is a timeout for parsing the proc mmap info, i.e. something like:
#define PROC_MAP_PARSE_TIMEOUT (50 * 1000000ULL)
Clarifies this and doesn't pollutes ctags like tools.
Thanks
- Arnaldo
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