From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [QUICKLIST 1/4] Quicklists for page table pages V5 From: Benjamin Herrenschmidt In-Reply-To: References: <20070409182509.8559.33823.sendpatchset@schroedinger.engr.sgi.com> <1176180337.8061.21.camel@localhost.localdomain> Content-Type: text/plain Date: Wed, 11 Apr 2007 14:18:41 +1000 Message-Id: <1176265121.8061.66.camel@localhost.localdomain> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, ak@suse.de, Paul Mackerras List-ID: On Tue, 2007-04-10 at 21:04 -0700, Christoph Lameter wrote: > On Tue, 10 Apr 2007, Benjamin Herrenschmidt wrote: > > > On Mon, 2007-04-09 at 11:25 -0700, Christoph Lameter wrote: > > > > > Quicklists for page table pages V5 > > > > Looks interesting, but unfortunately not very useful at this point for > > powerpc unless you remove the assumption that quicklists contain > > pages... > > Then quicklists wont be as simple anymore. > > > On powerpc, we currently use kmem cache slabs (though that isn't > > terribly node friendly) whose sizes depend on the page size. > > > > For a 4K page size kernel, we have 4 level page tables and use 2 caches, > > PTE and PGD pages are 4K (thus are PAGE_SIZE'd), and PMD & PUD are 1K. > > PTE and PGD could be run via quicklists? With PTEs you cover the most > common case. Quicklists using PGDs will allow to optimize using > preconstructed pages. > > Its probably best to keep the slabs for the 1K pages. > > > For a 64K page size kernel, we have 3 level page tables and we use 3 > > caches: a PGD pages are 128 bytes (yeah, not big heh...), our pmd > > pages are 32K (half a page) and PTE pages are PAGE_SIZE (64K). > > Ok so use quicklists for the PTEs and slab for the rest? A PGD of only 128 > bytes? Stuff one at the end of the mm_struct or the task struct? That way > you can avoid allocation overhead. Yeah, maybe... I need to think about it a bit more. I might be able to make the PMD a full page too. Ben. -- 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