Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760708AbXEaXsR (ORCPT ); Thu, 31 May 2007 19:48:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755775AbXEaXsE (ORCPT ); Thu, 31 May 2007 19:48:04 -0400 Received: from [198.99.130.12] ([198.99.130.12]:34907 "EHLO saraswathi.solana.com" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1755876AbXEaXsB (ORCPT ); Thu, 31 May 2007 19:48:01 -0400 Date: Thu, 31 May 2007 19:39:46 -0400 From: Jeff Dike To: Zach Brown Cc: Ingo Molnar , LKML , uml-devel Subject: Re: [PATCH] Syslets - Fix cachemiss_thread return value Message-ID: <20070531233946.GA12493@c2.user-mode-linux.org> References: <20070531181923.GA9904@c2.user-mode-linux.org> <20070531220716.GL5488@mami.zabbo.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070531220716.GL5488@mami.zabbo.net> User-Agent: Mutt/1.4.2.3i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1424 Lines: 32 On Thu, May 31, 2007 at 03:07:16PM -0700, Zach Brown wrote: > Can you explain what motivated you to send out this patch? > > It used to return 0. It was changed because, unlike the syslet > syscalls, sys_io_submit() doesn't have a simple 0 value to indicate > success. The current implementation wants to return the number of iocbs > that were processed, including the one which blocked, from the cachemiss > thread. So before calling into an operation it sets task_ret_ret() so > that the cachemiss thread can return it if it takes over. > task_ret_reg() is holding a return value that is being returned by the > cachemiss thread on behalf of a sys_io_submit() which blocked. > > When I made the change I didn't really audit its effect on the other > paths. I suppose it's time to do that, and you could help by telling me > if you saw something bad happen :). The bad thing was sys_async_exec returning -NOSYS every time a new cachemiss thread was created. Without this patch, you'll see sys_async_exec failures with either of the demos I sent out. Dunno about the existing ones, but I bet they do the same. Jeff -- Work email - jdike at linux dot intel dot com - 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/