linux-kernel - sys_rt_sigreturn calling sys

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Message-ID: <619ad6271001221346j19c9038bx8013e5b560d0c138@mail.gmail.com>
Date:	Fri, 22 Jan 2010 13:46:45 -0800
From:	Ivan Novick <novickivan@...il.com>
To:	linux-kernel@...r.kernel.org
Subject: sys_rt_sigreturn calling sys_futex?

Hello,

I have a userspace app that I profiled using SystemTap.

It says there are frequent calls to sys_futex which come from sys_rt_sigreturn.

It is true, that my app has many signal handler calls due to
frequently set timers in the code.

I had a look at the source for my kernel: Suse: linux-2.6.27.39-0.3
but I don't see any calls to futex from inside sys_rt_sigreturn.

Do you know if sys_rt_sigreturn is somehow calling sys_futex?

And if so, does this imply that ultra-frequent signal handling can
create a bottleneck between many processes in the sys_rt_sigreturn
system call trying to access a futex?

Thank you and regards,
Ivan Novick
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