Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756230AbYAISRO (ORCPT ); Wed, 9 Jan 2008 13:17:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754053AbYAISQ7 (ORCPT ); Wed, 9 Jan 2008 13:16:59 -0500 Received: from tetsuo.zabbo.net ([207.173.201.20]:59293 "EHLO tetsuo.zabbo.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753068AbYAISQ7 (ORCPT ); Wed, 9 Jan 2008 13:16:59 -0500 Message-ID: <47850F99.5020001@oracle.com> Date: Wed, 09 Jan 2008 10:16:57 -0800 From: Zach Brown User-Agent: Thunderbird 2.0.0.9 (Macintosh/20071031) MIME-Version: 1.0 To: Rusty Russell CC: linux-kernel@vger.kernel.org, Linus Torvalds , Ingo Molnar , Ulrich Drepper , Arjan van de Ven , Andrew Morton , Alan Cox , Evgeniy Polyakov , "David S. Miller" , Suparna Bhattacharya , Davide Libenzi , Jens Axboe , Thomas Gleixner , Dan Williams , Jeff Moyer , Simon Holm Thogersen , suresh.b.siddha@intel.com Subject: Re: [PATCH 5/6] syslets: add generic syslets infrastructure References: <1196983219534-git-send-email-zach.brown@oracle.com> <200801091303.58920.rusty@rustcorp.com.au> <478438B4.6010101@oracle.com> <200801091448.46241.rusty@rustcorp.com.au> In-Reply-To: <200801091448.46241.rusty@rustcorp.com.au> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1346 Lines: 30 >> Or do you mean the syscall return value ending up in the userspace >> completion event ring? That's mostly about being able to wait for >> pending syslets to complete. > > The latter. A ring is optimal for processing a huge number of requests, but > if you're really going to be firing off syslet threads all over the place > you're not going to be optimal anyway. And being able to point the return > value to the stack or into some datastructure is way nicer to code (zero > setup == easy to understand and easy to convert). One of Linus' rhetorical requirements for the syslets work is that we be able to wait for the result without spending overhead building up state in some completion context. The userland rings in the current syslet patches achieve that and don't seem outrageously complicated. I have a hard time getting worked up about this particular piece of the puzzle, though. If people are excited about *only* providing a pollable fd to collect the syslet completions, well, great, whatever. > This must be solved, yet all avenues seem crawling with worms. Yup. - z -- 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/