From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [PATCH] poll: Avoid extra wakeups in select/poll Date: Wed, 29 Apr 2009 11:22:40 +0200 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 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 To: Andi Kleen Return-path: 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 Content-Disposition: inline In-Reply-To: <20090429073539.GR27382@one.firstfloor.org> Sender: netdev-owner@vger.kernel.org List-ID: * 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