Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933568AbXBXWZW (ORCPT ); Sat, 24 Feb 2007 17:25:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933571AbXBXWZW (ORCPT ); Sat, 24 Feb 2007 17:25:22 -0500 Received: from x35.xmailserver.org ([64.71.152.41]:2106 "EHLO x35.xmailserver.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933568AbXBXWZV (ORCPT ); Sat, 24 Feb 2007 17:25:21 -0500 X-AuthUser: davidel@xmailserver.org Date: Sat, 24 Feb 2007 14:25:18 -0800 (PST) From: Davide Libenzi X-X-Sender: davide@alien.or.mcafeemobile.com To: Kyle Moffett cc: Ingo Molnar , Linux Kernel Mailing List , Linus Torvalds , Arjan van de Ven , Christoph Hellwig , Andrew Morton , Alan Cox , Ulrich Drepper , Zach Brown , Evgeniy Polyakov , "David S. Miller" , Suparna Bhattacharya , Jens Axboe , Thomas Gleixner Subject: Re: [patch 04/13] syslets: core code In-Reply-To: <21665A89-1BEE-459D-8ED1-ACCB352CF8A4@mac.com> Message-ID: References: <20070221211516.GD7579@elte.hu> <20070224070409.GB3357@elte.hu> <21665A89-1BEE-459D-8ED1-ACCB352CF8A4@mac.com> 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: 1848 Lines: 39 On Sat, 24 Feb 2007, Kyle Moffett wrote: > On Feb 24, 2007, at 16:10:33, Davide Libenzi wrote: > > On Sat, 24 Feb 2007, Ingo Molnar wrote: > > > the on/off calls are shaped in a way that makes them ultimately > > > vsyscall-able - the kernel only needs to know about the fact that we are > > > in a threadlet (so that the scheduler can do its special > > > push-head-to-another-context thing) - and this can be signalled via a > > > small user-space-side info structure as well, put into the TLS. > > > > IMO it's not a matter of speed. We'll have those two new syscalls, that I > > don't see other practical use for. IMO the best thing would be to hide all > > inside the sys_threadlet_exec (or whatever name). > > No, it absolutely is a matter of speed. The reason to have those two > implemented that way is so that they can be implemented as vsyscalls > completely in userspace. This means that on most modern platforms you can > implement the "make a threadlet when I block" semantic without even touching > kernel-mode. The way it's set up all you'd have to do is save some > parameters, set up a new callstack, and poke a "1" into a memory address in > the TLS. To stop, you effectively just poke a "0" into the spot in the TLS > and either return or terminate the thread. Right. I don't why but I got the implression Ingo's threadlet_exec example was just sketch code to be moved in a syscall. That's why I was talking about a sys_threadlet_exec. But yeah, it makes a lot of sense to turn threadlet_exec in a glibc thing, and play everything in userspace at that point. - 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/