From owner-cvs-src@FreeBSD.ORG  Wed Mar 19 07:44:15 2008
Return-Path: <owner-cvs-src@FreeBSD.ORG>
Delivered-To: cvs-src@hub.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 3C0AB106566B;
	Wed, 19 Mar 2008 07:44:15 +0000 (UTC)
	(envelope-from davidxu@FreeBSD.org)
Received: from freefall.freebsd.org (freefall.freebsd.org
	[IPv6:2001:4f8:fff6::28])
	by mx1.freebsd.org (Postfix) with ESMTP id 196388FC1D;
	Wed, 19 Mar 2008 07:44:15 +0000 (UTC)
	(envelope-from davidxu@FreeBSD.org)
Received: from apple.my.domain (root@localhost [127.0.0.1])
	by freefall.freebsd.org (8.14.2/8.14.2) with ESMTP id m2J7iBvc076399;
	Wed, 19 Mar 2008 07:44:12 GMT (envelope-from davidxu@freebsd.org)
Message-ID: <47E0C49D.8010807@freebsd.org>
Date: Wed, 19 Mar 2008 15:45:33 +0800
From: David Xu <davidxu@FreeBSD.org>
User-Agent: Thunderbird 2.0.0.9 (X11/20071211)
MIME-Version: 1.0
To: Jeff Roberson <jeff@FreeBSD.org>
References: <200803190735.m2J7ZEhO000502@repoman.freebsd.org>
In-Reply-To: <200803190735.m2J7ZEhO000502@repoman.freebsd.org>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject: Re: cvs commit: src/sys/kern subr_sleepqueue.c
X-BeenThere: cvs-src@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: CVS commit messages for the src tree <cvs-src.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/cvs-src>,
	<mailto:cvs-src-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/cvs-src>
List-Post: <mailto:cvs-src@freebsd.org>
List-Help: <mailto:cvs-src-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/cvs-src>,
	<mailto:cvs-src-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 19 Mar 2008 07:44:15 -0000

Jeff Roberson wrote:
> jeff        2008-03-19 07:35:14 UTC
> 
>   FreeBSD src repository
> 
>   Modified files:
>     sys/kern             subr_sleepqueue.c 
>   Log:
>    - At the top of sleepq_catch_signals() lock the thread and check TDF_NEEDSIGCHK
>      before doing the very expensive cursig() and related locking.  NEEDSIGCHK
>      is updated whenever our signal mask change or when a signal is delivered and
>      should be sufficient to avoid the more expensive tests.  This eliminates
>      another source of PROC_LOCK contention in multithreaded programs.
>   
>   Revision  Changes    Path
>   1.50      +12 -4     src/sys/kern/subr_sleepqueue.c
> 

This may break process suspension, a more completed patch is here: 
(though it is outdated):

http://people.freebsd.org/~davidxu/patch/PCATCH_optimize.patch

In one word, process suspending may be in progress, and the thread
should check it.

Regards,
David Xu