From owner-svn-src-head@FreeBSD.ORG Thu Nov 19 21:55:33 2009 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id CD99F106568B; Thu, 19 Nov 2009 21:55:33 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from cyrus.watson.org (cyrus.watson.org [65.122.17.42]) by mx1.freebsd.org (Postfix) with ESMTP id 988BB8FC08; Thu, 19 Nov 2009 21:55:33 +0000 (UTC) Received: from bigwig.baldwin.cx (66.111.2.69.static.nyinternet.net [66.111.2.69]) by cyrus.watson.org (Postfix) with ESMTPSA id 214D446B38; Thu, 19 Nov 2009 16:55:33 -0500 (EST) Received: from jhbbsd.hudson-trading.com (unknown [209.249.190.8]) by bigwig.baldwin.cx (Postfix) with ESMTPA id 583088A020; Thu, 19 Nov 2009 16:55:32 -0500 (EST) From: John Baldwin To: Jung-uk Kim Date: Thu, 19 Nov 2009 16:49:36 -0500 User-Agent: KMail/1.9.7 References: <200911182340.nAINeJ3W087652@svn.freebsd.org> <200911191115.11088.jkim@FreeBSD.org> In-Reply-To: <200911191115.11088.jkim@FreeBSD.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200911191649.37198.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.0.1 (bigwig.baldwin.cx); Thu, 19 Nov 2009 16:55:32 -0500 (EST) X-Virus-Scanned: clamav-milter 0.95.1 at bigwig.baldwin.cx X-Virus-Status: Clean X-Spam-Status: No, score=-2.5 required=4.2 tests=AWL,BAYES_00,RDNS_NONE autolearn=no version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on bigwig.baldwin.cx Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Robert Watson Subject: Re: svn commit: r199498 - in head/sys: amd64/amd64 i386/i386 net X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 19 Nov 2009 21:55:33 -0000 On Thursday 19 November 2009 11:15:01 am Jung-uk Kim wrote: > On Thursday 19 November 2009 03:26 am, Robert Watson wrote: > > On Wed, 18 Nov 2009, Jung-uk Kim wrote: > > > - Change internal function bpf_jit_compile() to return allocated > > > size of the generated binary and remove page size limitation for > > > userland. - Use contigmalloc(9)/contigfree(9) instead of > > > malloc(9)/free(9) to make sure the generated binary aligns > > > properly and make it physically contiguous. > > > > Is physical contiguity actually required here -- I would have > > thought virtual contiguity and alignment would be sufficient, in > > which case the normal trick is to allocate using malloc the size + > > min-align + 1 and then fudge the pointer forward until it's > > properly aligned. > > I don't believe it is strictly necessary but I assumed it might have > performance benefit for very big BPF programs although I have not > measured it. Also, contigmalloc(9)/contigfree(9) is too obvious to > ignore for this purpose. :-) Why would it have a performance benefit to have the pages be physically contiguous? contigmalloc() is expensive and should really only be used if you truly need contiguous memory. If you can get by with malloc(), just use malloc(). -- John Baldwin