From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <47547A79.2060206@redhat.com> Date: Mon, 03 Dec 2007 16:51:53 -0500 From: Chris Snook MIME-Version: 1.0 Subject: Re: [PATCH 2/2] powerpc: make 64K huge pages more reliable References: <474CF694.8040700@us.ibm.com> <20071203020648.GF26919@localhost.localdomain> In-Reply-To: <20071203020648.GF26919@localhost.localdomain> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: kniht@linux.vnet.ibm.com, linuxppc-dev , Linux Memory Management List List-ID: David Gibson wrote: > On Tue, Nov 27, 2007 at 11:03:16PM -0600, Jon Tollefson wrote: >> This patch adds reliability to the 64K huge page option by making use of >> the PMD for 64K huge pages when base pages are 4k. So instead of a 12 >> bit pte it would be 7 bit pmd and a 5 bit pte. The pgd and pud offsets >> would continue as 9 bits and 7 bits respectively. This will allow the >> pgtable to fit in one base page. This patch would have to be applied >> after part 1. > > Hrm.. shouldn't we just ban 64K hugepages on a 64K base page size > setup? There's not a whole lot of point to it, after all... > Actually, it sounds to me like an ideal way to benchmark the efficiency of the hugepage implementation and VM effects, without the TLB performance obscuring the results. I agree that it's not something people will want to do very often, but the same can be said about quite a lot of strange things that we allow just because there's no fundamental reason why they cannot be. -- Chris -- 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