>
> Em Wed, Jun 10, 2015 at 03:46:04AM -0400, kan.li...@intel.com escreveu:
> > perf top reads all threads' /proc/xxx/maps. If there is any threads
> > which generating a keeping growing huge /proc/xxx/maps, perf will do
> > infinite loop in perf_event__synthesize_mmap_events.
> > This patch fixes this issue by adding a time out to force stop this
> > kind of endless mmap processing.
> >
> > Reported-by: Huang, Ying <ying.hu...@intel.com>
> > Signed-off-by: Kan Liang <kan.li...@intel.com>
>
> So we will silently stop processing those events?
>
> We will make progress, no doubt, but I think the user needs to be warned
> about this situation, so that later on when/if samples for those maps
> appear and don't get resolved at least we will know that this is the reason.
>
I will add warning message for this kind of time out.
Thanks,
Kan
> - Arnaldo
>
> > ---
> > tools/perf/util/event.c | 7 ++++++-
> > 1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c index
> > 793b150..0df7f2a9 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)
> > +
> > int perf_event__synthesize_mmap_events(struct perf_tool *tool,
> > union perf_event *event,
> > pid_t pid, pid_t tgid,
> > @@ -222,6 +224,7 @@ int
> perf_event__synthesize_mmap_events(struct
> > perf_tool *tool, {
> > char filename[PATH_MAX];
> > FILE *fp;
> > + unsigned long long t;
> > int rc = 0;
> >
> > if (machine__is_default_guest(machine))
> > @@ -240,6 +243,7 @@ int
> perf_event__synthesize_mmap_events(struct perf_tool *tool,
> > }
> >
> > event->header.type = PERF_RECORD_MMAP2;
> > + t = rdclock();
> >
> > while (1) {
> > char bf[BUFSIZ];
> > @@ -250,7 +254,8 @@ int
> perf_event__synthesize_mmap_events(struct perf_tool *tool,
> > size_t size;
> > ssize_t n;
> >
> > - if (fgets(bf, sizeof(bf), fp) == NULL)
> > + if ((fgets(bf, sizeof(bf), fp) == NULL) ||
> > + ((rdclock() - t) > MMAP_TIMEOUT))
> > break;
> >
> > /* ensure null termination since stack will be reused. */
> > --
> > 1.8.3.1
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