From: Oleg Nesterov <oleg@tv-sign.ru>
To: Christoph Lameter <clameter@engr.sgi.com>
Cc: Ravikiran Thirumalai <kiran@scalex86.org>,
Shai Fultheim <shai@scalex86.org>,
Nippun Goel <nippung@calsoftinc.com>,
linux-kernel@vger.kernel.org, Andrew Morton <akpm@osdl.org>
Subject: Re: [rfc][patch] Avoid taking global tasklist_lock for single threadedprocess at getrusage()
Date: Wed, 28 Dec 2005 15:38:39 +0300 [thread overview]
Message-ID: <43B2874F.F41A9299@tv-sign.ru> (raw)
In-Reply-To: Pine.LNX.4.62.0512271220380.27174@schroedinger.engr.sgi.com
Christoph Lameter wrote:
>
> On Sat, 24 Dec 2005, Oleg Nesterov wrote:
>
> > I can't understand this. 'p' can do clone(CLONE_THREAD) immediately
> > after 'if (!thread_group_empty(p))' check.
>
> Only if p != current. As discussed later the lockless approach is
> intened to only be used if p == current.
Unless I missed something this function (getrusage_both) is called
from wait_noreap_copyout,
> +++ linux-2.6.15-rc6/kernel/exit.c 2005-12-23 10:42:16.000000000 -0800
> @@ -38,7 +38,7 @@
> extern void sem_exit (void);
> extern struct task_struct *child_reaper;
>
> -int getrusage(struct task_struct *, int, struct rusage __user *);
> +int getrusage_both(struct task_struct *, struct rusage __user *);
>
> static void exit_mm(struct task_struct * tsk);
>
> @@ -994,7 +994,7 @@
> struct siginfo __user *infop,
> struct rusage __user *rusagep)
> {
> - int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
> + int retval = rusagep ? getrusage_both(p, rusagep) : 0;
> put_task_struct(p);
(the diff lacks '-p' parameter)
So p != current.
Oleg.
next prev parent reply other threads:[~2005-12-28 11:23 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-24 17:52 [rfc][patch] Avoid taking global tasklist_lock for single threaded process at getrusage() Oleg Nesterov
2005-12-27 20:21 ` Christoph Lameter
2005-12-28 12:38 ` Oleg Nesterov [this message]
2005-12-28 18:33 ` [rfc][patch] Avoid taking global tasklist_lock for single threadedprocess " Ravikiran G Thirumalai
2005-12-28 22:57 ` Ravikiran G Thirumalai
2005-12-30 17:57 ` Oleg Nesterov
2006-01-04 23:16 ` Ravikiran G Thirumalai
2006-01-05 19:17 ` Oleg Nesterov
2006-01-06 9:46 ` Ravikiran G Thirumalai
2006-01-06 17:23 ` Christoph Lameter
2006-01-06 19:46 ` Ravikiran G Thirumalai
2006-03-20 18:04 ` Oleg Nesterov
2006-03-22 22:18 ` Ravikiran G Thirumalai
2006-03-23 18:18 ` Oleg Nesterov
2006-01-06 23:52 ` Andrew Morton
2006-01-08 11:49 ` Oleg Nesterov
2006-01-08 19:58 ` Ravikiran G Thirumalai
2006-01-09 18:55 ` Oleg Nesterov
2006-01-09 20:54 ` Ravikiran G Thirumalai
2006-01-10 19:03 ` Oleg Nesterov
2006-01-16 20:56 ` Ravikiran G Thirumalai
2006-01-17 19:59 ` Oleg Nesterov
2006-01-17 19:52 ` Ravikiran G Thirumalai
2006-01-18 9:17 ` Oleg Nesterov
2006-01-03 18:18 ` Christoph Lameter
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