From owner-freebsd-stable@FreeBSD.ORG  Tue Dec 12 12:49:25 2006
Return-Path: <owner-freebsd-stable@FreeBSD.ORG>
X-Original-To: stable@freebsd.org
Delivered-To: freebsd-stable@FreeBSD.ORG
Received: from localhost.my.domain (localhost [127.0.0.1])
	by hub.freebsd.org (Postfix) with ESMTP id 71A2216A403;
	Tue, 12 Dec 2006 12:49:24 +0000 (UTC)
	(envelope-from davidxu@freebsd.org)
From: David Xu <davidxu@freebsd.org>
To: freebsd-stable@freebsd.org
Date: Tue, 12 Dec 2006 20:49:21 +0800
User-Agent: KMail/1.8.2
References: <20061113084430.GE59604@dimma.mow.oilspace.com>
	<200612071118.52922.davidxu@freebsd.org>
	<20061212122221.GE39171@dkirhlarov.mow.oilspace.com>
In-Reply-To: <20061212122221.GE39171@dkirhlarov.mow.oilspace.com>
MIME-Version: 1.0
Content-Type: text/plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
Message-Id: <200612122049.21525.davidxu@freebsd.org>
Cc: stable@freebsd.org, Dmitriy Kirhlarov <dimma@higis.ru>
Subject: Re: RELENG_6 panic under heavy load
X-BeenThere: freebsd-stable@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Production branch of FreeBSD source code <freebsd-stable.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-stable>, 
	<mailto:freebsd-stable-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-stable>
List-Post: <mailto:freebsd-stable@freebsd.org>
List-Help: <mailto:freebsd-stable-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-stable>,
	<mailto:freebsd-stable-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 12 Dec 2006 12:49:25 -0000

On Tuesday 12 December 2006 20:22, Dmitriy Kirhlarov wrote:
> On Thu, Dec 07, 2006 at 11:18:52AM +0800, David Xu wrote:
> > On Thursday 16 November 2006 19:15, Gleb Smirnoff wrote:
> > > On Thu, Nov 16, 2006 at 01:24:36PM +0300, Gleb Smirnoff wrote:
> > > T>   I wonder why UMA was suspected to be the problem. Dima gave
> > > T> me access to the core. Here are more details from the trace:
> > >
> > > It looks like a race between two threads in one process. Look here:
> >
> > Can you try the patch ?
> > http://people.freebsd.org/~davidxu/patch/ksegrp_preempt.patch
>
> I've tested it. This patch works also, but with a little bit different
> behaviour. With patch from jhb@ I got LA 7-8, with this patch I have
> LA 5-6, same as on unpatched system. But it seems to me, that system
> is less interactive, compared to jhb@ patch.
>
> WBR
> Dmitriy

jhb patch is incomplete, it implies that every place a thread is doing state
transition and waking another thread up should be patched, there is
other code in kern_sig.c unpatched, though I don't know other places,
but the code maybe_preempt_in_ksegrp should be synced with
maybe_preempt, it should fix all problems. the LA you have seen is lower
than jhb might be a nature of KSEGRP, but I am not sure, if you program
forces all threads to be system-scope, it might fix the problem. 

David Xu