From: "Dorau, Lukasz" <lukasz.dorau@intel.com>
To: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>,
"Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com>,
"David S. Miller" <davem@davemloft.net>,
Masami Hiramatsu <mhiramat@kernel.org>,
"linux-trace-users@vger.kernel.org"
<linux-trace-users@vger.kernel.org>
Cc: "Slusarz, Marcin" <marcin.slusarz@intel.com>,
"Jelinek, Sarah" <sarah.jelinek@intel.com>,
"Chernookyi, Vitalii" <vitalii.chernookyi@intel.com>,
"Buella, Gabor" <gabor.buella@intel.com>
Subject: Why return probes of some syscalls sometimes are not called?
Date: Thu, 9 Mar 2017 13:44:38 +0000 [thread overview]
Message-ID: <D9FFE20C522965449E182ACE73889AEB4868177B@irsmsx105.ger.corp.intel.com> (raw)
Hi,
Could someone explain me why return probes of some syscalls (for example: futex, poll, epoll_wait) sometimes are not called?
It can be reproduced using the following bash script:
https://gist.github.com/ldorau/c439d9ec7635409a5016c42e3a9121ec
Here are results gathered from 60 seconds test run on kernel 4.9.12 (Fedora 24):
futex: p 56904 r 5489 (90% did not return (51415))
poll: p 43466 r 7703 (82% did not return (35763))
epoll_wait: p 73366 r 23551 (67% did not return (49815))
The whole log is attached below.
Lukasz
---
# ./test_kprobes.sh 60
Will trace using following kprobe_events:
r:kprobes/r_futex sys_futex
p:kprobes/p_futex sys_futex
r:kprobes/r_poll sys_poll
p:kprobes/p_poll sys_poll
r:kprobes/r_epoll_wait sys_epoll_wait
p:kprobes/p_epoll_wait sys_epoll_wait
r:kprobes/r_select sys_select
p:kprobes/p_select sys_select
r:kprobes/r_fork sys_fork
p:kprobes/p_fork sys_fork
r:kprobes/r_vfork sys_vfork
p:kprobes/p_vfork sys_vfork
r:kprobes/r_mmap sys_mmap
p:kprobes/p_mmap sys_mmap
r:kprobes/r_open sys_open
p:kprobes/p_open sys_open
r:kprobes/r_close sys_close
p:kprobes/p_close sys_close
r:kprobes/r_write sys_write
p:kprobes/p_write sys_write
r:kprobes/r_read sys_read
p:kprobes/p_read sys_read
Results (60 sec):
futex: p 56904 r 5489 (90% did not return (51415))
poll: p 43466 r 7703 (82% did not return (35763))
epoll_wait: p 73366 r 23551 (67% did not return (49815))
select: p 13355 r 13351 (0% did not return (4))
fork: p 0 r 0 (OK)
vfork: p 0 r 0 (OK)
mmap: p 4328 r 4328 (OK)
open: p 4579 r 4579 (OK)
close: p 7163 r 7163 (OK)
write: p 22769 r 22769 (OK)
read: p 40014 r 40014 (OK)
next reply other threads:[~2017-03-09 13:44 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-09 13:44 Dorau, Lukasz [this message]
2017-03-09 13:58 ` Why return probes of some syscalls sometimes are not called? Mathieu Desnoyers
2017-03-09 14:44 ` Steven Rostedt
2017-03-09 14:57 ` Steven Rostedt
[not found] ` <1231722663.1343.1489071698914.JavaMail.zimbra@efficios.com>
2017-03-09 15:20 ` Steven Rostedt
[not found] ` <D9FFE20C522965449E182ACE73889AEB486818F2@irsmsx105.ger.corp.intel.com>
2017-03-09 15:38 ` Steven Rostedt
2017-03-09 17:00 ` Masami Hiramatsu
2017-03-09 18:19 ` Chernookyi, Vitalii
2017-03-10 10:51 ` Masami Hiramatsu
2017-03-13 9:09 ` Dorau, Lukasz
2017-03-16 10:01 ` Masami Hiramatsu
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