From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755718AbXD0M0E (ORCPT ); Fri, 27 Apr 2007 08:26:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755747AbXD0M0D (ORCPT ); Fri, 27 Apr 2007 08:26:03 -0400 Received: from smtp104.mail.mud.yahoo.com ([209.191.85.214]:31491 "HELO smtp104.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1755718AbXD0M0A (ORCPT ); Fri, 27 Apr 2007 08:26:00 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:X-YMail-OSG:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=GdyPuMW1Y23UUM0atTjeXgHPQMw8GPtXNlrf5ab904BR0BHQTWBVfU/u9RFLvApWIQIofvpKuOIruECBd984+3AFxJlEP66KbgTbFDwum+RXCubksI8rt5xH+XFNcCyMplwdl2zzc11PBBjB7petowo3MiV66qk2z0Haczc8YXs= ; X-YMail-OSG: RNm9rw4VM1ldkaFIv3xqjTd7BwXjp2R7IpjO3N6FtZ6grKUOTSxJ6APE761Wp5dFASkPlMUcPg-- Message-ID: <4631EBC8.4060003@yahoo.com.au> Date: Fri, 27 Apr 2007 22:25:44 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051007 Debian/1.7.12-1 X-Accept-Language: en MIME-Version: 1.0 To: Christoph Lameter CC: Paul Mackerras , Andrew Morton , David Chinner , linux-kernel@vger.kernel.org, Mel Gorman , William Lee Irwin III , Jens Axboe , Badari Pulavarty , Maxim Levitsky Subject: Re: [00/17] Large Blocksize Support V3 References: <20070424222105.883597089@sgi.com> <20070426190438.3a856220.akpm@linux-foundation.org> <20070427022731.GF65285596@melbourne.sgi.com> <20070426195357.597ffd7e.akpm@linux-foundation.org> <20070427042046.GI65285596@melbourne.sgi.com> <20070426221528.655d79cb.akpm@linux-foundation.org> <20070426235542.bad7035a.akpm@linux-foundation.org> <17969.55533.59287.509889@cargo.ozlabs.ibm.com> <4631E173.7000204@yahoo.com.au> In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Christoph Lameter wrote: > On Fri, 27 Apr 2007, Nick Piggin wrote: > > >>For the TLB issue, higher order pagecache doesn't help. If distros >>ship with a 4K page size on powerpc, and use some larger pages in >>the pagecache, some people are still going to get angry because >>they wanted to use 64K pages... But I agree 64K pages is too big >>for most things anyway, and 16 would be better as a default (which >>hopefully x86-64 will get one day). > > > Powerpc supports multiple pagesizes. Maybe we could make mmap use those > page sizes some day if we had a variable order page cache. Your stands on > the issue means that powerpc will be forever crippled and not be able to > use its full potential. Linus's favourite jokes about powerpc mmu being crippled forever, aside ;) This seems like just speculation. I would not be against something which, without, would "cripple" some relevant hardware, but you are just handwaving at this point. And you are still ignoring the alternatives. >>Anyway, for io performance, there are alternatives, dispite what >>some people seem to be saying. We can submit larger sglists to the >>device for larger ios, which Jens is looking at (which could help >>all types of workloads, not just those with sequential large file >>IO). > > > Right this could help but it is not addressing the basic requirement for > devices that need large contiguuos chunks of memory for I/O. Did you read the last paragraph? Or anything Andrew's been writing? "After that, I'd find it amusing if HBAs worth thousands of $ have trouble looking up sglists at the relatively glacial pace that IO requires, and/or can't spare a few more K for reasonable sglist sizes, but if that is really the case, then we could use iommus and/or just attempt to put physically contiguous pages in pagecache, rather than require it." -- SUSE Labs, Novell Inc.