Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932440AbXB1VqP (ORCPT ); Wed, 28 Feb 2007 16:46:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932446AbXB1VqP (ORCPT ); Wed, 28 Feb 2007 16:46:15 -0500 Received: from x35.xmailserver.org ([64.71.152.41]:4903 "EHLO x35.xmailserver.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932440AbXB1VqO (ORCPT ); Wed, 28 Feb 2007 16:46:14 -0500 X-AuthUser: davidel@xmailserver.org Date: Wed, 28 Feb 2007 13:46:09 -0800 (PST) From: Davide Libenzi X-X-Sender: davide@alien.or.mcafeemobile.com To: Ingo Molnar cc: Ulrich Drepper , Linux Kernel Mailing List , Linus Torvalds , Arjan van de Ven , Christoph Hellwig , Andrew Morton , Alan Cox , Zach Brown , Evgeniy Polyakov , "David S. Miller" , Suparna Bhattacharya , Jens Axboe , Thomas Gleixner Subject: Re: [patch 00/13] Syslets, "Threadlets", generic AIO support, v3 In-Reply-To: <20070228212306.GA27127@elte.hu> Message-ID: References: <20070221211355.GA7302@elte.hu> <20070221233111.GB5895@elte.hu> <45DCD9E5.2010106@redhat.com> <20070222074044.GA4158@elte.hu> <20070228094522.GA17716@elte.hu> <20070228202156.GA15846@elte.hu> <20070228212306.GA27127@elte.hu> X-GPG-FINGRPRINT: CFAE 5BEE FD36 F65E E640 56FE 0974 BF23 270F 474E X-GPG-PUBLIC_KEY: http://www.xmailserver.org/davidel.asc MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2437 Lines: 61 On Wed, 28 Feb 2007, Ingo Molnar wrote: > * Davide Libenzi wrote: > > > Did you hide all the complexity of the userspace atom decoding inside > > another function? :) > > no, i made the 64-bit and 32-bit structures layout-compatible. This > makes the 32-bit structure as large as the 64-bit ones, but that's not a > big issue, compared to the simplifications it brings. Do you have a new version to review? > > > But i'm happy to change the syslet API in any sane way, and did so > > > based on feedback from Jens who is actually using them. > > > > Wouldn't you agree on a simple/parallel execution engine [...] > > the thing is, there's almost zero overhead from having those basic > things like conditions and the ->next link, and they make it so much > more capable. As usual my biggest problem is that you are not trying to > use syslets at all - you are only trying to get rid of them ;-) My > purpose with syslets is to enable a syslet to do almost anything that > user-space could do too, as simply as possible. Syslets could even > allocate user-space memory and then use it (i dont think we actually > want to do that though). That doesnt mean arbitrary complex code > /should/ be done via syslets, or that it wont be significantly slower > than what user-space can do, but i'd not like to artificially dumb the > engine down. I'm totally willing to simplify/shrink the vectoring of > arguments and just about anything else, but your proposals so far (such > as your return-value-embedded-in-atom suggestion) all kill important > aspects of the engine. Ok, we're past the error code in the atom, as Linus pointed out ;) How about this, with async_wait returning asynid's back to a userspace ring buffer? struct syslet_utaom { long *result; unsigned long asynid; unsigned long nr_sysc; unsigned long params[8]; }; My problem with the syslets in their current form is, do we have a real use for them that justify the extra complexity inside the kernel? Or with a simple/parellel async submission, coupled with threadlets, we can cover a pretty broad range of real life use cases? - Davide - 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/