Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758836AbZD2JYU (ORCPT ); Wed, 29 Apr 2009 05:24:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752379AbZD2JXy (ORCPT ); Wed, 29 Apr 2009 05:23:54 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:55946 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751633AbZD2JXx (ORCPT ); Wed, 29 Apr 2009 05:23:53 -0400 Date: Wed, 29 Apr 2009 11:22:40 +0200 From: Ingo Molnar To: Andi Kleen Cc: Andrew Morton , Eric Dumazet , linux kernel , David Miller , cl@linux.com, jesse.brandeburg@intel.com, netdev@vger.kernel.org, haoki@redhat.com, mchan@broadcom.com, davidel@xmailserver.org Subject: Re: [PATCH] poll: Avoid extra wakeups in select/poll Message-ID: <20090429092240.GA30403@elte.hu> References: <49F3308B.1030507@cosmosbay.com> <20090426.020411.157511269.davem@davemloft.net> <49F43B8F.2050907@cosmosbay.com> <87ab60rh8t.fsf@basil.nowhere.org> <49F71B63.8010503@cosmosbay.com> <20090429002049.4bbc8105.akpm@linux-foundation.org> <20090429073539.GR27382@one.firstfloor.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090429073539.GR27382@one.firstfloor.org> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 889 Lines: 26 * Andi Kleen wrote: > > Seems that this is a virtuous patch even though Christoph is struggling > > a bit to test it? > > The main drawback is that the select/poll data structures will get > larger. That could cause regression in theory. [...] Current size of struct poll_table_entry is 0x38 on 64-bit kernels. Adding the key will make it 0x40 - which is not only a power of two but also matches cache line size on most modern CPUs. So the size of this structure is ideal now and arithmetics on the poll table have become simpler as well. So the patch has my ack: Acked-by: Ingo Molnar Ingo -- 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/