Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S269409AbUJFWRE (ORCPT ); Wed, 6 Oct 2004 18:17:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269494AbUJFWQv (ORCPT ); Wed, 6 Oct 2004 18:16:51 -0400 Received: from mailhost.tue.nl ([131.155.2.7]:59405 "EHLO mailhost.tue.nl") by vger.kernel.org with ESMTP id S269409AbUJFWPP (ORCPT ); Wed, 6 Oct 2004 18:15:15 -0400 Date: Thu, 7 Oct 2004 00:15:12 +0200 From: Andries Brouwer To: Alan Cox Cc: davem@davemloft.net, Martijn Sipkema , Andries Brouwer , Joris van Rantwijk , Linux Kernel Mailing List Subject: Re: UDP recvmsg blocks after select(), 2.6 bug? Message-ID: <20041006221512.GE4523@pclin040.win.tue.nl> References: <1097080873.29204.57.camel@localhost.localdomain> <20041006193053.GC4523@pclin040.win.tue.nl> <1097090625.29707.9.camel@localhost.localdomain> <00f201c4abf1$0444c3e0$161b14ac@boromir> <1097094326.29871.9.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1097094326.29871.9.camel@localhost.localdomain> User-Agent: Mutt/1.4.1i X-Spam-DCC: : Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1316 Lines: 31 On Wed, Oct 06, 2004 at 09:25:28PM +0100, Alan Cox wrote: > The current setup has so far been found to break one app, after what > three years. It can almost double performance. In this case it is very > much POSIX_ME_HARDER, and perhaps longer term suggests the posix/sus > people should revisit their API design. Maybe. Have we really investigated and concluded that there is no reasonable way to follow POSIX and not harm performance? I would hope that checksum failure is not the fast path, so at zeroth sight, not having looked at the code, it seems that we could do rather elaborate things on checksum failure if we wanted to. One such thing might be to raise a flag "I/O error seen since last read" where the flag is cleared by read and causes an EIO when there is no other input. (There may be many objections - maybe such a setup would break more user space programs. Or maybe there are more ways select is broken than just the "discarded because of bad checksum" way. But it seems too early to just say "too bad, our select is not the POSIX one".) Andries - 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/