From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 24 Apr 2007 13:03:52 +0200 From: Nick Piggin Subject: Re: [patch 13/44] mm: restore KERNEL_DS optimisations Message-ID: <20070424110352.GB32738@wotan.suse.de> References: <20070424012346.696840000@suse.de> <20070424013434.155713000@suse.de> <20070424104318.GA13268@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070424104318.GA13268@infradead.org> Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Hellwig Cc: Andrew Morton , Linux Filesystems , Mark Fasheh , Linux Memory Management List-ID: On Tue, Apr 24, 2007 at 11:43:18AM +0100, Christoph Hellwig wrote: > On Tue, Apr 24, 2007 at 11:23:59AM +1000, Nick Piggin wrote: > > Restore the KERNEL_DS optimisation, especially helpful to the 2copy write > > path. > > > > This may be a pretty questionable gain in most cases, especially after the > > legacy 2copy write path is removed, but it doesn't cost much. > > Well, it gets removed later and sets a bad precedence. Instead of > adding hacks we should have proper methods for kernel-space read/writes. > Especially as the latter are a lot simpler and most of the magic > in this patch series is not needed. I'll start this work once > your patch series is in. It was removed earlier and put back in here. I agree it isn't so important, but again it does help that the patchset introduces no obvious regression. You could remove it in your patchset? > In general there seems to be a lot of stuff in the earlier patches > that just goes away later and doesn't make much sense in the series. > Is there a good reason not to simply consolidate out those changes > completely? I guess the first half of the patchset -- the slow deadlock fix for the old prepare_write path -- came about because that's the only reasonable way I could find to fix it. I initially thought it would take a lot longer to convert all filesystems and that we might want to stay compatible for a while, which is why I wanted to ensure that was working. Basically I can't really see which ones you think I should merge and be able retain a working kernel? Granted there are a couple of bugfixes and some slightly orthogonal cleanups in there, but I just thought I'd submit them in the same series because it was a little easier for me. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org