Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759022AbXITR40 (ORCPT ); Thu, 20 Sep 2007 13:56:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756967AbXITR4T (ORCPT ); Thu, 20 Sep 2007 13:56:19 -0400 Received: from x35.xmailserver.org ([64.71.152.41]:42757 "EHLO x35.xmailserver.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751839AbXITR4S (ORCPT ); Thu, 20 Sep 2007 13:56:18 -0400 X-AuthUser: davidel@xmailserver.org Date: Thu, 20 Sep 2007 10:56:14 -0700 (PDT) From: Davide Libenzi X-X-Sender: davide@alien.or.mcafeemobile.com To: Eric Dumazet cc: Nagendra Tomar , David Miller , netdev@vger.kernel.org, Linux Kernel Mailing List Subject: Re: [PATCH 2.6.23-rc6 Resending] NETWORKING : Edge Triggered EPOLLOUT events get missed for TCP sockets In-Reply-To: <46F20F24.1020900@cosmosbay.com> Message-ID: References: <331107.71046.qm@web53704.mail.re2.yahoo.com> <46F20F24.1020900@cosmosbay.com> X-GPG-FINGRPRINT: CFAE 5BEE FD36 F65E E640 56FE 0974 BF23 270F 474E X-GPG-PUBLIC_KEY: http://www.xmailserver.org/davidel.asc MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1494 Lines: 35 On Thu, 20 Sep 2007, Eric Dumazet wrote: > Does it means that with your patch each ACK on a ET managed socket will > trigger an epoll event ? > > Maybe your very sensitive high throuput appication needs to set a flag or > something at socket level to ask for such a behavior. > > The default should stay as is. That is an event should be sent only if someone > cared about the wakeup. Unfortunately f_op->poll() does not let the caller to specify the events it's interested in, that would allow to split send/recevie wait queues and better detect read/write cases. The detection of a waitqueue_active(->sk_wr_sleep) would work fine in detecting is someone is actually waiting for a write, w/out the false positives triggered by the read-waiters. That would be a very sane thing to do, but would require a big&dumb change to all the ->poll around (that could be automated by a script - devices not caring about the events hint can just continue to use the single queue like they currently do), and a more critical and gradual change of all the devices that wants to take advantage of it. That way, no more magic bits are needed, and a simple waitqueue_active() would tell you if someone is waiting for write-space events. - Davide - 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/