From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262014AbVCHLkL (ORCPT ); Tue, 8 Mar 2005 06:40:11 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262022AbVCHLj0 (ORCPT ); Tue, 8 Mar 2005 06:39:26 -0500 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:42927 "EHLO fgwmail5.fujitsu.co.jp") by vger.kernel.org with ESMTP id S262014AbVCHLgM (ORCPT ); Tue, 8 Mar 2005 06:36:12 -0500 Message-ID: <422D8F2A.4010002@jp.fujitsu.com> Date: Tue, 08 Mar 2005 20:40:26 +0900 From: KAMEZAWA Hiroyuki User-Agent: Mozilla Thunderbird 1.0 (Windows/20041206) X-Accept-Language: ja, en-us, en MIME-Version: 1.0 To: Mel Gorman Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, clameter@sgi.com Subject: Re: [PATCH] 2/2 Prezeroing large blocks of pages during allocation Version 4 References: <20050307194021.E6A86E594@skynet.csn.ul.ie> <422D42BF.4060506@jp.fujitsu.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Mel Gorman wrote: >>> >>> >>Now, 5bits per MAX_ORDER pages. >>I think it is simpler to use "char[]" for representing type of memory alloc >>type than bitmap. >> >> >> > >Possibly, but it would also use up that bit more space. That map could be >condensed to 3 bits but would make it that bit (no pun) more complex and >difficult to merge. On the other hand, it would be faster to use a char[] >as it would be an array-index lookup to get a pageblock type rather than a >number of bit operations. > >So, it depends on what people know to be better in general because I have >not measured it to know for a fact. Is it better to use char[] and use >array indexes rather than bit operations or is it better to leave it as a >bitmap and condense it later when things have settled down? > > Hmm, Okay, I'll wait for condensed version. BTW, in space consumption/cache view, does using bitmap have real benefit ? Thanks -- Kame