From: Matt Fleming <matt@console-pimps.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Oleg Nesterov <oleg@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andi Kleen <andi@firstfloor.org>, Tejun Heo <tj@kernel.org>,
linux-kernel@vger.kernel.org, Tony Luck <tony.luck@intel.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
David Mosberger-Tang <davidm@egauge.net>
Subject: Re: [RFC][PATCH 0/5] Signal scalability series
Date: Tue, 04 Oct 2011 09:20:17 +0100 [thread overview]
Message-ID: <1317716417.3375.91.camel@mfleming-mobl1.ger.corp.intel.com> (raw)
In-Reply-To: <alpine.LFD.2.02.1110032345050.1489@ionos>
On Tue, 2011-10-04 at 00:13 +0200, Thomas Gleixner wrote:
>
> After staring a bit at your patch I think that you need to tackle that
> from a different angle.
>
> The main nuisance of sighand->siglock is the exit race protection and
> that's why we need to take it for evrything and some more.
Right.
> In order to distangle the posix-(cpu)-timer and other stuffs
> protection from that single lock, you need to introduce "independent"
> locks which basically do the same dance as lock_task_sighand() does
> and have to be taken in the exit() path in a well defined order before
> manipulating task->sighand.
Yeah, I've been trying to avoid changing the tsk->sighand stuff (you'll
notice that lock_task_sighand() still works as before in this patch
series) because when I've attempted it before it has always resulted in
much more complicated code (and coming from me, that's saying
something!).
> That way you still cover the exit races, but you can break up the
> locking for particular subsystems w/o the need of (much) nesting.
Yeah, that approach seems interesting. I'll have a look at that, thanks!
--
Matt Fleming, Intel Open Source Technology Center
next prev parent reply other threads:[~2011-10-04 8:20 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-30 15:12 [RFC][PATCH 0/5] Signal scalability series Matt Fleming
2011-09-30 15:12 ` [RFC][PATCH 1/5] signal: Document signal locking rules Matt Fleming
2011-09-30 15:12 ` [RFC][PATCH 2/5] signal: Add rwlock to protect sighand->action Matt Fleming
2011-09-30 15:25 ` Peter Zijlstra
2011-09-30 15:56 ` Matt Fleming
2011-09-30 15:12 ` [RFC][PATCH 3/5] signal: Reduce sighand->siglock hold time in get_signal_to_deliver() Matt Fleming
2011-09-30 15:12 ` [RFC][PATCH 4/5] signal: Add signal->ctrl_lock for job control Matt Fleming
2011-09-30 15:30 ` Peter Zijlstra
2011-09-30 15:36 ` Matt Fleming
2011-09-30 15:12 ` [RFC][PATCH 5/5] signal: Split siglock into shared_siglock and per-thread siglock Matt Fleming
2011-09-30 16:52 ` [RFC][PATCH 0/5] Signal scalability series Oleg Nesterov
2011-09-30 18:54 ` Oleg Nesterov
2011-09-30 20:00 ` Matt Fleming
2011-09-30 23:56 ` Tejun Heo
2011-10-01 10:16 ` Matt Fleming
2011-10-01 13:03 ` Peter Zijlstra
2011-10-03 1:38 ` Tejun Heo
2011-10-03 13:56 ` Thomas Gleixner
2011-10-04 7:37 ` Tejun Heo
2011-10-03 13:07 ` Oleg Nesterov
2011-10-03 15:22 ` Peter Zijlstra
2011-10-04 17:14 ` Oleg Nesterov
2011-10-04 17:52 ` Oleg Nesterov
2011-10-04 17:54 ` Linus Torvalds
2011-10-04 18:13 ` Oleg Nesterov
2011-10-03 13:16 ` Oleg Nesterov
2011-10-04 8:56 ` Matt Fleming
2011-10-04 17:29 ` Oleg Nesterov
2011-09-30 22:30 ` Andi Kleen
2011-10-01 9:35 ` Matt Fleming
2011-10-03 15:28 ` Linus Torvalds
2011-10-03 15:43 ` Matt Fleming
2011-10-03 16:35 ` Oleg Nesterov
2011-10-03 20:58 ` Matt Fleming
2011-10-03 21:45 ` Linus Torvalds
2011-10-03 22:13 ` Thomas Gleixner
2011-10-04 8:20 ` Matt Fleming [this message]
2011-10-04 17:39 ` Oleg Nesterov
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