Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268993AbUJQAcr (ORCPT ); Sat, 16 Oct 2004 20:32:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268989AbUJQAcq (ORCPT ); Sat, 16 Oct 2004 20:32:46 -0400 Received: from mail1.webmaster.com ([216.152.64.168]:61448 "EHLO mail1.webmaster.com") by vger.kernel.org with ESMTP id S268987AbUJQAad (ORCPT ); Sat, 16 Oct 2004 20:30:33 -0400 From: "David Schwartz" To: "Linux-Kernel@Vger. Kernel. Org" Subject: RE: UDP recvmsg blocks after select(), 2.6 bug? Date: Sat, 16 Oct 2004 17:30:23 -0700 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.6604 (9.0.2911.0) In-Reply-To: <20041017000626.GA27055@mark.mielke.cc> X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 Importance: Normal X-Authenticated-Sender: joelkatz@webmaster.com X-Spam-Processed: mail1.webmaster.com, Sat, 16 Oct 2004 17:07:03 -0700 (not processed: message from trusted or authenticated source) X-MDRemoteIP: 206.171.168.138 X-Return-Path: davids@webmaster.com X-MDaemon-Deliver-To: linux-kernel@vger.kernel.org Reply-To: davids@webmaster.com X-MDAV-Processed: mail1.webmaster.com, Sat, 16 Oct 2004 17:07:05 -0700 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1117 Lines: 28 > I don't think he is, but if he is: > > I'm not sure that either is reasonable behaviour. The socket buffers > don't increase or decrease at run time, do they? If they do shrink at > run time, this is news to me... The socket buffers are not guaranteed to indicate a particular number of bytes in a sense that it meaningful to the application. In fact, on Linux, they don't mean application bytes. In any event, we aren't talking about any particular implementation, we are talking about a standard. So what Linux does or doesn't do in response to memory pressure isn't relevant. What's relevant is what the standard actually guarantees and what the semantics of the protocols themselves are. UDP is not reliable. Packets can be dropped, mangled, and lost. Nothing in POSIX prohibits an implementation from dropping a packet right before you call 'recvmsg'. DS - 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/