Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753828Ab0HRS5L (ORCPT ); Wed, 18 Aug 2010 14:57:11 -0400 Received: from fieldses.org ([174.143.236.118]:48563 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753428Ab0HRS5J (ORCPT ); Wed, 18 Aug 2010 14:57:09 -0400 Date: Wed, 18 Aug 2010 14:54:56 -0400 From: "J. Bruce Fields" To: Andi Kleen Cc: Neil Brown , Alan Cox , "Patrick J. LoPresti" , linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-kernel Subject: Re: Proposal: Use hi-res clock for file timestamps Message-ID: <20100818185456.GD13050@fieldses.org> References: <87aaolwar8.fsf@basil.nowhere.org> <20100817174134.GA23176@fieldses.org> <20100817182920.GD18161@basil.fritz.box> <20100817190447.GA28049@fieldses.org> <20100817203941.729830b7@lxorguk.ukuu.org.uk> <20100817192937.GD26609@fieldses.org> <20100818155359.66b9ddb6@notabene> <20100818175040.GA6567@basil.fritz.box> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100818175040.GA6567@basil.fritz.box> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 715 Lines: 18 On Wed, Aug 18, 2010 at 07:50:40PM +0200, Andi Kleen wrote: > > - nfsd updates it whenever it reads an mtime out of an inode that matches > > current_fs_time to the granularity of 1/HZ. > > That means you have a very very hot cache line on a larger system > if there are a lot of mtime changes. Probably a bad idea. Only if those mtime changes are also followed immediately by nfsd reads of the mtime. That will be the typical case for nfsd writes, though. --b. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/