linux-perf-users.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
* uretprobe occasionally fires twice
@ 2017-08-08 18:56 Benjamin King
  0 siblings, 0 replies; only message in thread
From: Benjamin King @ 2017-08-08 18:56 UTC (permalink / raw)
  To: linux-perf-users

Hi,
 
I have placed a uprobe and a uretprobe on the same function in libc. When
perf record'ing a larger test where the function is called from multiple
threads, I can occasionally see the following sequence of events in a 'perf
script':
  
  1) uretprobe fires
  2) uprobe fires
  3) uretprobe fires again

More specifically, I am tracing libc's realloc. Since I trace the size of
the memory in question, I think that the uretprobe in 1) is called at
function entry.

This only happens occasionally and I unfortunately I could not reproduce it
with a small testcase yet.

'perf script' prints two warnings:
  * Processed 17216221 events and lost 2 chunks!
  * 114 out of order events recorded.

Could this explain the duplicated output? Are there other known circumstances
where a uretprobe could be unreliable in some way?

Cheers,
  Benjamin

^ permalink raw reply	[flat|nested] only message in thread

only message in thread, other threads:[~2017-08-08 18:57 UTC | newest]

Thread overview: (only message) (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2017-08-08 18:56 uretprobe occasionally fires twice Benjamin King

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).