From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 22 Oct 2002 12:26:55 -0200 (BRST) From: Rik van Riel Subject: Re: [PATCH 2.5.43-mm2] New shared page table patch 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: "Eric W. Biederman" Cc: "Martin J. Bligh" , Bill Davidsen , Dave McCracken , Andrew Morton , Linux Kernel , Linux Memory Management List-ID: On 21 Oct 2002, Eric W. Biederman wrote: > "Martin J. Bligh" writes: > > > > So why has no one written a pte_chain reaper? It is perfectly sane > > > to allocate a swap entry and move an entire pte_chain to the swap > > > cache. > > > > I think the underlying subsystem does not easily allow for dynamic regeneration, > > so it's non-trivial. > > We swap pages out all of the time in 2.4.x, and that is all I was > suggesting swap out some but not all of the pages, on a very long > pte_chain. And swapping out a page is not terribly complex, unless > something very drastic has changed. Imagine a slightly larger than normal Oracle server. Say 5000 processes with 1 GB of shared memory. Just the page tables needed to map this memory would take up 5 GB of RAM ... with shared page tables we only need 1 MB of page tables. The corresponding reduction in rmaps is a nice bonus, but hardly any more dramatic than the page table overhead. In short, we really really want shared page tables. regards, Rik -- Bravely reimplemented by the knights who say "NIH". http://www.surriel.com/ http://distro.conectiva.com/ Current spamtrap: october@surriel.com -- 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/