From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: broken VM in 2.4.10-pre9 References: From: ebiederm@xmission.com (Eric W. Biederman) Date: 17 Sep 2001 02:06:46 -0600 In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org Return-Path: To: Rik van Riel Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: Rik van Riel writes: > On 16 Sep 2001, Michael Rothwell wrote: > > > Is there a way to tell the VM to prune its cache? Or a way to limit > > the amount of cache it uses? > > Not yet, I'll make a quick hack for this when I get back next > week. It's pretty obvious now that the 2.4 kernel cannot get > enough information to select the right pages to evict from > memory. Hmm. Perhaps or perhaps it is using the information poorly. There is an alternative approach to have better aging information. An address_space can be allocated per mm_struct. And all of the anonymous pages can be allocated to that address_space. The address_space can then have an array or better a tree of extents that list which indexes correspond to which swap pages. With some pages not being backed. Getting the allocation of indices correct so that merging will work is a little trickier then now, as is the case of a private writeable mapping of a file. But in a lot of other ways the logic becomes simpler. > For 2.5 I'm making a VM subsystem with reverse mappings, the > first iterations are giving very sweet performance so I will > continue with this project regardless of what other kernel > hackers might say ;) Do you have any arguments for the reverse mappings or just for some of the other side effects that go along with them? Eric -- 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/