From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932096AbWIKRBb (ORCPT ); Mon, 11 Sep 2006 13:01:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751261AbWIKRBb (ORCPT ); Mon, 11 Sep 2006 13:01:31 -0400 Received: from outpipe-village-512-1.bc.nu ([81.2.110.250]:35234 "EHLO lxorguk.ukuu.org.uk") by vger.kernel.org with ESMTP id S1751235AbWIKRBa (ORCPT ); Mon, 11 Sep 2006 13:01:30 -0400 Subject: Re: Spinlock debugging From: Alan Cox To: Andrew Bird Cc: linux-kernel@vger.kernel.org In-Reply-To: <200609111738.21818.ajb@spheresystems.co.uk> References: <200609111632.27484.ajb@spheresystems.co.uk> <1157992570.23085.169.camel@localhost.localdomain> <200609111738.21818.ajb@spheresystems.co.uk> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Mon, 11 Sep 2006 18:24:52 +0100 Message-Id: <1157995492.23085.191.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.6.2 (2.6.2-1.fc5.5) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Ar Llu, 2006-09-11 am 17:38 +0100, ysgrifennodd Andrew Bird: > Alan > Yes, I have low_latency set for kernels lower than 2.6.17. I'm currently > testing using 2.6.15. When you mention 'write method for flow control' do you > mean for software XON/XOFF etc? Yes Basically in low_latency the following is valid driver receives bytes flush_to_ldisc ldisc calls driver write methods That means if you have a shared lock for read/write you want to drop it after you've bashed the hardware and before you flush_to_ldisc. Remember the IRQ handler is not re-entrant so another IRQ of the same number won't cause further I/O and out of order receives. Alan