Em Wed, Jun 10, 2015 at 03:46:04AM -0400, [email protected] 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 <[email protected]>
> Signed-off-by: Kan Liang <[email protected]>
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.
- 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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