Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268001AbUIIWsu (ORCPT ); Thu, 9 Sep 2004 18:48:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268286AbUIIWst (ORCPT ); Thu, 9 Sep 2004 18:48:49 -0400 Received: from fw.osdl.org ([65.172.181.6]:50101 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S268001AbUIIWsl (ORCPT ); Thu, 9 Sep 2004 18:48:41 -0400 Date: Thu, 9 Sep 2004 15:52:26 -0700 From: Andrew Morton To: Marcelo Tosatti Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH] cacheline align pagevec structure Message-Id: <20040909155226.714dc704.akpm@osdl.org> In-Reply-To: <20040909163929.GA4484@logos.cnet> References: <20040909163929.GA4484@logos.cnet> X-Mailer: Sylpheed version 0.9.7 (GTK+ 1.2.10; i586-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 969 Lines: 23 Marcelo Tosatti wrote: > > I do not see a problem with changing pagevec to "15" page pointers either, > Andrew, is there a special reason for that "16"? Is intentional to align > to 64 kbytes (IO device alignment)? I dont think that matters much because > of the elevator which sorts and merges requests anyway? No, it was just a randomly-chosen batching factor. The tradeoff here is between a) lock acquisition frequency versus lock hold time (increasing the size helps). b) icache misses versus dcache misses. (increasing the size probably hurts). I suspect that some benefit would be seen from making the size very small (say, 4). And on some machines, making it larger might help. - 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/