From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755354Ab0CWAWN (ORCPT ); Mon, 22 Mar 2010 20:22:13 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:34726 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754841Ab0CWAWL (ORCPT ); Mon, 22 Mar 2010 20:22:11 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 From: KOSAKI Motohiro To: Mel Gorman Subject: Re: [PATCH 06/11] Export fragmentation index via /proc/extfrag_index Cc: kosaki.motohiro@jp.fujitsu.com, Andrew Morton , Andrea Arcangeli , Christoph Lameter , Adam Litke , Avi Kivity , David Rientjes , Rik van Riel , linux-kernel@vger.kernel.org, linux-mm@kvack.org In-Reply-To: <20100317113326.GD12388@csn.ul.ie> References: <20100317114321.4C9A.A69D9226@jp.fujitsu.com> <20100317113326.GD12388@csn.ul.ie> Message-Id: <20100323050910.A473.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.50.07 [ja] Date: Tue, 23 Mar 2010 09:22:04 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > > + /* > > > + * Index is between 0 and 1 so return within 3 decimal places > > > + * > > > + * 0 => allocation would fail due to lack of memory > > > + * 1 => allocation would fail due to fragmentation > > > + */ > > > + return 1000 - ( (1000+(info->free_pages * 1000 / requested)) / info->free_blocks_total); > > > +} > > > > Dumb question. > > your paper (http://portal.acm.org/citation.cfm?id=1375634.1375641) says > > fragmentation_index = 1 - (TotalFree/SizeRequested)/BlocksFree > > but your code have extra '1000+'. Why? > > To get an approximation to three decimal places. Do you mean this is poor man's round up logic? Why don't you use DIV_ROUND_UP? likes following, return 1000 - (DIV_ROUND_UP(info->free_pages * 1000 / requested) / info->free_blocks_total); From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id 2A7B86B01AD for ; Mon, 22 Mar 2010 20:22:10 -0400 (EDT) Received: from m3.gw.fujitsu.co.jp ([10.0.50.73]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o2N0M6U6018714 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Tue, 23 Mar 2010 09:22:06 +0900 Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 645FE45DE52 for ; Tue, 23 Mar 2010 09:22:06 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.fujitsu.co.jp [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 4299245DD76 for ; Tue, 23 Mar 2010 09:22:06 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 24A17E08005 for ; Tue, 23 Mar 2010 09:22:06 +0900 (JST) Received: from m106.s.css.fujitsu.com (m106.s.css.fujitsu.com [10.249.87.106]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id B0614E08001 for ; Tue, 23 Mar 2010 09:22:05 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [PATCH 06/11] Export fragmentation index via /proc/extfrag_index In-Reply-To: <20100317113326.GD12388@csn.ul.ie> References: <20100317114321.4C9A.A69D9226@jp.fujitsu.com> <20100317113326.GD12388@csn.ul.ie> Message-Id: <20100323050910.A473.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Tue, 23 Mar 2010 09:22:04 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Mel Gorman Cc: kosaki.motohiro@jp.fujitsu.com, Andrew Morton , Andrea Arcangeli , Christoph Lameter , Adam Litke , Avi Kivity , David Rientjes , Rik van Riel , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: > > > + /* > > > + * Index is between 0 and 1 so return within 3 decimal places > > > + * > > > + * 0 => allocation would fail due to lack of memory > > > + * 1 => allocation would fail due to fragmentation > > > + */ > > > + return 1000 - ( (1000+(info->free_pages * 1000 / requested)) / info->free_blocks_total); > > > +} > > > > Dumb question. > > your paper (http://portal.acm.org/citation.cfm?id=1375634.1375641) says > > fragmentation_index = 1 - (TotalFree/SizeRequested)/BlocksFree > > but your code have extra '1000+'. Why? > > To get an approximation to three decimal places. Do you mean this is poor man's round up logic? Why don't you use DIV_ROUND_UP? likes following, return 1000 - (DIV_ROUND_UP(info->free_pages * 1000 / requested) / info->free_blocks_total); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org