From owner-cvs-src@FreeBSD.ORG  Sun Jan 29 08:35:41 2006
Return-Path: <owner-cvs-src@FreeBSD.ORG>
X-Original-To: cvs-src@FreeBSD.org
Delivered-To: cvs-src@FreeBSD.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id AE39116A420;
	Sun, 29 Jan 2006 08:35:41 +0000 (GMT)
	(envelope-from scottl@samsco.org)
Received: from pooker.samsco.org (pooker.samsco.org [168.103.85.57])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 3AD9B43D45;
	Sun, 29 Jan 2006 08:35:40 +0000 (GMT)
	(envelope-from scottl@samsco.org)
Received: from [192.168.254.11] (junior.samsco.home [192.168.254.11])
	(authenticated bits=0)
	by pooker.samsco.org (8.13.4/8.13.4) with ESMTP id k0T8Zbu4057133;
	Sun, 29 Jan 2006 01:35:37 -0700 (MST)
	(envelope-from scottl@samsco.org)
Message-ID: <43DC7E5B.9080906@samsco.org>
Date: Sun, 29 Jan 2006 01:35:39 -0700
From: Scott Long <scottl@samsco.org>
User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.7.12) Gecko/20051230
X-Accept-Language: en-us, en
MIME-Version: 1.0
To: Nate Lawson <nate@root.org>
References: <20060129082512.6EBA116A477@hub.freebsd.org>
	<43DC7DEB.7050200@root.org>
In-Reply-To: <43DC7DEB.7050200@root.org>
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit
X-Spam-Status: No, score=-1.4 required=3.8 tests=ALL_TRUSTED autolearn=failed 
	version=3.1.0
X-Spam-Checker-Version: SpamAssassin 3.1.0 (2005-09-13) on pooker.samsco.org
Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org,
	Scott Long <scottl@FreeBSD.org>, cvs-all@FreeBSD.org
Subject: Re: cvs commit: src/sys/vm vm_contig.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: Sun, 29 Jan 2006 08:35:41 -0000

Nate Lawson wrote:
> Scott Long wrote:
> 
>> scottl      2006-01-29 08:24:54 UTC
>>
>>   FreeBSD src repository
>>
>>   Modified files:
>>     sys/vm               vm_contig.c   Log:
>>   The change a few years ago of having contigmalloc start its scan at 
>> the top
>>   of physical RAM instead of the bottom was a sound idea, but the 
>> implementation
>>   left a lot to be desired.  Scans would spend considerable time 
>> looking at
>>   pages that are above of the address range given by the caller, and 
>> multiple
>>   calls (like what happens in busdma) would spend more time on top of 
>> that
>>   rescanning the same pages over and over.
> 
> 
> Interesting.
> 
>> Index: src/sys/vm/vm_contig.c
>> diff -u src/sys/vm/vm_contig.c:1.47 src/sys/vm/vm_contig.c:1.48
>> --- src/sys/vm/vm_contig.c:1.47    Thu Jan 26 05:51:26 2006
>> +++ src/sys/vm/vm_contig.c    Sun Jan 29 08:24:54 2006
>> @@ -387,7 +387,9 @@
>>      vm_offset_t size;
>>      vm_paddr_t phys;
>>      vm_page_t pga = vm_page_array;
>> -    int i, pass, pqtype, start;
>> +    static vm_pindex_t np = 0;
>> +    static vm_pindex_t start = 0;
>> +    int i, pass, pqtype;
> 
> 
> What lock protects access to these static variables?
> 

The whole function is serialized by Giant.

Scott