Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946790AbXBJAPF (ORCPT ); Fri, 9 Feb 2007 19:15:05 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1946791AbXBJAPF (ORCPT ); Fri, 9 Feb 2007 19:15:05 -0500 Received: from smtp.osdl.org ([65.172.181.24]:56754 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1946790AbXBJAPD (ORCPT ); Fri, 9 Feb 2007 19:15:03 -0500 Date: Fri, 9 Feb 2007 16:12:45 -0800 (PST) From: Linus Torvalds To: Eric Dumazet cc: Zach Brown , Linux Kernel Mailing List , linux-aio@kvack.org, Suparna Bhattacharya , Benjamin LaHaise , Ingo Molnar Subject: Re: [PATCH 0 of 4] Generic AIO by scheduling stacks In-Reply-To: <45CD0C07.5060601@cosmosbay.com> Message-ID: References: <45CD0C07.5060601@cosmosbay.com> 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: 1351 Lines: 40 On Sat, 10 Feb 2007, Eric Dumazet wrote: > > Well, I guess if the original program was mono-threaded, and syscall used > fget_light(), we might have a problem here if the child try a close(). So you > may have to disable fget_light() magic if async call is the originator of the > syscall. Yes. All the issues that I already brought up with Zach's patches are still there. This doesn't really change any of them. Any optimization that checks for "am I single-threaded" will need to be aware of pending and running async things. With my patch, any _running_ async things will always be seen as normal clones, but the pending ones won't. So you'd need to effectively change anything that looks like if (atomic_read(¤t->mm->count) == 1) .. do some simplified version .. into if (!current->async_cookie && atomic_read(..) == 1) .. do the simplified thing .. to make it safe. I think we only do it for fget_light and some VM TLB simplification, so it shouldn't be a big burden to check. Side note: the real issues still remain. The interfaces, and the performance testing. Linus - 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/