From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755531Ab1BORFn (ORCPT ); Tue, 15 Feb 2011 12:05:43 -0500 Received: from e39.co.us.ibm.com ([32.97.110.160]:60167 "EHLO e39.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754097Ab1BORFk (ORCPT ); Tue, 15 Feb 2011 12:05:40 -0500 Subject: Re: [PATCH 0/5] fix up /proc/$pid/smaps to not split huge pages From: Dave Hansen To: Andrea Arcangeli Cc: Eric B Munson , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michael J Wolf In-Reply-To: <20110215170152.GF5935@random.random> References: <20110209195406.B9F23C9F@kernel> <20110215165510.GA2550@mgebm.net> <20110215170152.GF5935@random.random> Content-Type: text/plain; charset="ANSI_X3.4-1968" Date: Tue, 15 Feb 2011 09:05:25 -0800 Message-ID: <1297789525.9829.9616.camel@nimitz> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2011-02-15 at 18:01 +0100, Andrea Arcangeli wrote: > > The entire mapping is contained in a THP but the > > KernelPageSize shows 4kb. For cases where the mapping might > > have mixed page sizes this may be okay, but for this > > particular mapping the 4kb page size is wrong. > > I'm not sure this is a bug, if the mapping grows it may become 4096k > but the new pages may be 4k. There's no such thing as a > vma_mmu_pagesize in terms of hugepages because we support graceful > fallback and collapse/split on the fly without altering the vma. So I > think 4k is correct here How about we bump MMUPageSize for mappings that are _entirely_ huge pages, but leave it at 4k for mixed mappings? Anyone needing more detail than that can use the new AnonHugePages count. KernelPageSize is pretty ambiguous, and we could certainly make the argument that the kernel is or can still deal with things in 4k blocks. -- Dave From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with ESMTP id 724978D0039 for ; Tue, 15 Feb 2011 12:05:40 -0500 (EST) Received: from d03relay03.boulder.ibm.com (d03relay03.boulder.ibm.com [9.17.195.228]) by e34.co.us.ibm.com (8.14.4/8.13.1) with ESMTP id p1FGs8TZ007512 for ; Tue, 15 Feb 2011 09:54:08 -0700 Received: from d03av04.boulder.ibm.com (d03av04.boulder.ibm.com [9.17.195.170]) by d03relay03.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p1FH5VwB102394 for ; Tue, 15 Feb 2011 10:05:31 -0700 Received: from d03av04.boulder.ibm.com (loopback [127.0.0.1]) by d03av04.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p1FH38Os031576 for ; Tue, 15 Feb 2011 10:03:08 -0700 Subject: Re: [PATCH 0/5] fix up /proc/$pid/smaps to not split huge pages From: Dave Hansen In-Reply-To: <20110215170152.GF5935@random.random> References: <20110209195406.B9F23C9F@kernel> <20110215165510.GA2550@mgebm.net> <20110215170152.GF5935@random.random> Content-Type: text/plain; charset="ANSI_X3.4-1968" Date: Tue, 15 Feb 2011 09:05:25 -0800 Message-ID: <1297789525.9829.9616.camel@nimitz> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrea Arcangeli Cc: Eric B Munson , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michael J Wolf On Tue, 2011-02-15 at 18:01 +0100, Andrea Arcangeli wrote: > > The entire mapping is contained in a THP but the > > KernelPageSize shows 4kb. For cases where the mapping might > > have mixed page sizes this may be okay, but for this > > particular mapping the 4kb page size is wrong. > > I'm not sure this is a bug, if the mapping grows it may become 4096k > but the new pages may be 4k. There's no such thing as a > vma_mmu_pagesize in terms of hugepages because we support graceful > fallback and collapse/split on the fly without altering the vma. So I > think 4k is correct here How about we bump MMUPageSize for mappings that are _entirely_ huge pages, but leave it at 4k for mixed mappings? Anyone needing more detail than that can use the new AnonHugePages count. KernelPageSize is pretty ambiguous, and we could certainly make the argument that the kernel is or can still deal with things in 4k blocks. -- Dave -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org