From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932110AbVH3DQO (ORCPT ); Mon, 29 Aug 2005 23:16:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932111AbVH3DQO (ORCPT ); Mon, 29 Aug 2005 23:16:14 -0400 Received: from smtp205.mail.sc5.yahoo.com ([216.136.129.95]:49498 "HELO smtp205.mail.sc5.yahoo.com") by vger.kernel.org with SMTP id S932110AbVH3DQN (ORCPT ); Mon, 29 Aug 2005 23:16:13 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=Vfo5LBUI1+TI32xtQoGtHQYicspz+5qJ6KQjYs2nNiLjm/qSFlLTc5bVmNRhTyMmipp4RG2pK8o5UZ2mwgho6oBja9OWSSHDJp2u+ueaHJz/Qi5o3Oa5Da14so2FE6LtFTNjo/5namB30okhuqzD8xjN6PpkINRHQDfpSYKTtQg= ; Message-ID: <4313CA1E.3000605@yahoo.com.au> Date: Tue, 30 Aug 2005 12:53:18 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.8) Gecko/20050513 Debian/1.7.8-1 X-Accept-Language: en MIME-Version: 1.0 To: James Bottomley CC: Sonny Rao , Andrew Morton , Linux Kernel Subject: Re: [PATCH] make radix tree gang lookup faster by using a bitmap search References: <1125159996.5159.8.camel@mulgrave> <20050827105355.360bd26a.akpm@osdl.org> <1125276312.5048.22.camel@mulgrave> <20050828175233.61cada23.akpm@osdl.org> <1125278389.5048.30.camel@mulgrave> <20050828183531.0b4d6f2d.akpm@osdl.org> <1125285994.5048.40.camel@mulgrave> <4312830C.8000308@yahoo.com.au> <20050829164144.GC9508@localhost.localdomain> <4313AEC9.3050406@yahoo.com.au> <1125369981.5089.106.camel@mulgrave> In-Reply-To: <1125369981.5089.106.camel@mulgrave> 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 James Bottomley wrote: >On Tue, 2005-08-30 at 10:56 +1000, Nick Piggin wrote: > > >>Gang lookup is mainly used on IO paths but also on truncate, >>which is a reasonably fast path on some workloads (James, >>this is my suggestion for what you should test - truncate). >> > >Actually, I don't think I can test this. In order to show a difference >between index 5 and index 6 on 32 bit, I'd have to deal with files > 4GB >in size. My 32 bit machines are the voyagers and only have 4GB discs. > >The machine with all the huge discs, is, naturally, ia64. > > Sorry, I meant for testing your gang lookup speedups. For testing regular lookups, yeah that's more difficult. For a microbenchmark you can use sparse files, which can be a good trick for testing pagecache performance without the IO. Nick Send instant messages to your online friends http://au.messenger.yahoo.com