From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 20 Apr 1998 22:55:31 +0100 Message-Id: <199804202155.WAA03972@dax.dcs.ed.ac.uk> From: "Stephen C. Tweedie" MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Subject: I've got some patches to integrate, too... In-Reply-To: References: Sender: owner-linux-mm@kvack.org To: "Benjamin C.R. LaHaise" Cc: "Eric W. Biederman" , linux-mm@kvack.org List-ID: Hi, On Wed, 15 Apr 1998 11:11:07 -0400 (EDT), "Benjamin C.R. LaHaise" said: > Which reminds me: Stephen, what's the state of your irq and smp patches > for page cache addition/removal. I'm getting a bit more free time now, so > perhaps I can play with them a bit (maybe we should have a common cvs > tree...). Sorry, I've been offline, away in Colorado, for over a week, or I'd have answered this earlier... The deferred pageout stuff (lazy page stealing) seems to work pretty well. It is rock solid when doing large compiles on a 6mb box, which stresses swapping pretty heavily. However, there is still a bug --- I can reproduce a copy-on-write violation occasionally when running one of my VM stress tests (I get a demand-zero page when I expect a non-zero value, so there's a pte getting lost in there somewhere). That's the only failure mode I can reproduce right now. Right now I've got Linux Expo and Usenix deadlines approaching fast, so there's a limit to how much time I can spend debugging code which is not going to be integrated until 2.3. I can't promise to get the lazy page code debugged in the next couple of weeks. With the feature freeze in place, I guess there's a big question mark over whether this code can get included in 2.2. If it doesn't, then what we really need to concentrate on is the memory fragmentation issues in 2.1, not the new 2.2 features. I spent a lot of time last week thinking about this, and there are a number of things we can do in 2.1 which will help enormously. I'll write them up in a day or two (right now I'm still catching up my mail backlog). We can definitely improve things without making major wholesale changes to the way VM works at the minute, even if it's not going to give us quite the performance or power that the really new code promises. I guess that Linus really has to make the call whether or not we risk destabilising the existing VM by adding the new code now, or whether that is a 2.3 issue. If it is a 2.3 thing, then 2.2 has more urgent problems which need addressing as a higher priority than adding new functionality. We can still track the new VM code, but as a separate branch which won't be integrated until 2.3 development starts (much like the new net code which was integrated at the start of 1.3 development). --Stephen