From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <20010927014431.C2164@bug.ucw.cz> Date: Thu, 27 Sep 2001 01:44:31 +0200 From: Pavel Machek Subject: Re: broken VM in 2.4.10-pre9 References: <20010925005033.A137@bug.ucw.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: ; from Marcelo Tosatti on Wed, Sep 26, 2001 at 03:22:01PM -0300 Sender: owner-linux-mm@kvack.org Return-Path: To: Marcelo Tosatti Cc: Alan Cox , "Eric W. Biederman" , Daniel Phillips , Rob Fuller , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: Hi! > > > > So my suggestion was to look at getting anonymous pages backed by what > > > > amounts to a shared memory segment. In that vein. By using an extent > > > > based data structure we can get the cost down under the current 8 bits > > > > per page that we have for the swap counts, and make allocating swap > > > > pages faster. And we want to cluster related swap pages anyway so > > > > an extent based system is a natural fit. > > > > > > Much of this goes away if you get rid of both the swap and anonymous page > > > special cases. Back anonymous pages with the "whoops everything I write here > > > vanishes mysteriously" file system and swap with a swapfs > > > > What exactly is anonymous memory? I thought it is what you do when you > > want to malloc(), but you want to back that up by swap, not /dev/null. > > Anonymous memory is memory which is not backed by a filesystem or a > device. eg: malloc()ed memory, shmem, mmap(MAP_PRIVATE) on a file (which > will create anonymous memory as soon as the program which did the mmap > writes to the mapped memory (COW)), etc. So... how can alan propose to back anonymous memory with /dev/null? [see above] It should be backed by swap, no? Pavel -- I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care." Panos Katsaloulis describing me w.r.t. patents at discuss@linmodems.org -- 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/