Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751792AbXBVTiK (ORCPT ); Thu, 22 Feb 2007 14:38:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751793AbXBVTiJ (ORCPT ); Thu, 22 Feb 2007 14:38:09 -0500 Received: from x35.xmailserver.org ([64.71.152.41]:4721 "EHLO x35.xmailserver.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751792AbXBVTiI (ORCPT ); Thu, 22 Feb 2007 14:38:08 -0500 X-AuthUser: davidel@xmailserver.org Date: Thu, 22 Feb 2007 11:38:03 -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: <20070222074044.GA4158@elte.hu> Message-ID: References: <20070221211355.GA7302@elte.hu> <20070221233111.GB5895@elte.hu> <45DCD9E5.2010106@redhat.com> <20070222074044.GA4158@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: 1912 Lines: 42 On Thu, 22 Feb 2007, Ingo Molnar wrote: > > * Ulrich Drepper wrote: > > > Ingo Molnar wrote: > > > in terms of AIO, the best queueing model is i think what the kernel uses > > > internally: freely ordered, with barrier support. > > > > Speaking of AIO, how do you imagine lio_listio is implemented? If > > there is no asynchronous syscall it would mean creating a threadlet > > for each request but this means either waiting or creating > > several/many threads. > > my current thinking is that special-purpose (non-programmable, static) > APIs like aio_*() and lio_*(), where every last cycle of performance > matters, should be implemented using syslets - even if it is quite > tricky to write syslets (which they no doubt are - just compare the size > of syslet-test.c to threadlet-test.c). So i'd move syslets into the same > category as raw syscalls: pieces of the raw infrastructure between the > kernel and glibc, not an exposed API to apps. [and even if we keep them > in that category they still need quite a bit of API work, to clean up > the 32/64-bit issues, etc.] Now that chains of syscalls can be way more easily handled with clets^wthreadlets, why would we need the whole syslets crud inside? Why can't aio_* be implemented with *simple* (or parallel/unrelated) syscall submit w/out the burden of a complex, limiting and heavy API (I won't list all the points against syslets, because I already did it enough times)? The compat layer only is so bad to not be even funny. Look at the code. Only removing the syslets crud would prolly cut 40% of it. And we did not even touch the compat code yet. - 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/