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SubjectRe: [PATCH 0/2] perf: Redesign trace events reordering
On Wed, May 05, 2010 at 12:48:47AM -0500, Tom Zanussi wrote:
> Hi Frederic,
>
> On Wed, 2010-05-05 at 02:03 +0200, Frederic Weisbecker wrote:
> > I recently noticed that the new reordering design is broken
> > when it deals with tons of events.
> >
> > This patchset provides another algorithm to deal with that,
> > tested without any problem.
> >
> > And since it involves more frequent flushes, I guess it could
> > plug nicely with the live mode.
>
> Very nice! I tried these out with live mode and it seems to work fine,
> after applying the patch below.
>
> I initially had a problem with 'unexpected end of event stream' errors,
> then noticed that the FINISHED_ROUND events were basically just headers
> with no data, which caused the read of the 0-length payload to appear as
> end-of-stream.
>
> I'll do some more testing (and fix some warnings in the scripts that
> this mode seems to elicit), but it seems so far to work pretty well for
> live mode...
>
> Tom


Cool, I'm applying your patch then,

Thanks.




>
> From: Tom Zanussi <tzanussi@gmail.com>
> Date: Wed, 5 May 2010 00:27:40 -0500
> Subject: [PATCH] perf/live-mode: handle payload-less events
>
> Some events, such as the PERF_RECORD_FINISHED_ROUND event consist of
> only an event header and no data. In this case, a 0-length payload
> will be read, and the 0 return value will be wrongly interpreted as an
> 'unexpected end of event stream'.
>
> This patch allows for proper handling of data-less events by skipping
> 0-length reads.
>
> Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
> ---
> tools/perf/util/session.c | 19 +++++++++++--------
> 1 files changed, 11 insertions(+), 8 deletions(-)
>
> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> index 9401909..00ab298 100644
> --- a/tools/perf/util/session.c
> +++ b/tools/perf/util/session.c
> @@ -696,15 +696,18 @@ more:
> p = &event;
> p += sizeof(struct perf_event_header);
>
> - err = do_read(self->fd, p, size - sizeof(struct perf_event_header));
> - if (err <= 0) {
> - if (err == 0) {
> - pr_err("unexpected end of event stream\n");
> - goto done;
> - }
> + if (size - sizeof(struct perf_event_header)) {
> + err = do_read(self->fd, p,
> + size - sizeof(struct perf_event_header));
> + if (err <= 0) {
> + if (err == 0) {
> + pr_err("unexpected end of event stream\n");
> + goto done;
> + }
>
> - pr_err("failed to read event data\n");
> - goto out_err;
> + pr_err("failed to read event data\n");
> + goto out_err;
> + }
> }
>
> if (size == 0 ||
> --
> 1.6.4.GIT
>
>
>



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