From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from d01relay04.pok.ibm.com (d01relay04.pok.ibm.com [9.56.227.236]) by e2.ny.us.ibm.com (8.13.8/8.13.8) with ESMTP id m8MFtvNG021744 for ; Mon, 22 Sep 2008 11:55:57 -0400 Received: from d01av02.pok.ibm.com (d01av02.pok.ibm.com [9.56.224.216]) by d01relay04.pok.ibm.com (8.13.8/8.13.8/NCO v9.1) with ESMTP id m8MFtv26218586 for ; Mon, 22 Sep 2008 11:55:57 -0400 Received: from d01av02.pok.ibm.com (loopback [127.0.0.1]) by d01av02.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m8MFtu95032689 for ; Mon, 22 Sep 2008 11:55:56 -0400 Subject: Re: [PATCH 1/2] Report the pagesize backing a VMA in /proc/pid/smaps From: Dave Hansen In-Reply-To: <1222047492-27622-2-git-send-email-mel@csn.ul.ie> References: <1222047492-27622-1-git-send-email-mel@csn.ul.ie> <1222047492-27622-2-git-send-email-mel@csn.ul.ie> Content-Type: text/plain Date: Mon, 22 Sep 2008 08:55:55 -0700 Message-Id: <1222098955.8533.50.camel@nimitz> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Mel Gorman Cc: LKML , Linux-MM List-ID: On Mon, 2008-09-22 at 02:38 +0100, Mel Gorman wrote: > It is useful to verify that a hugepage-aware application is using the expected > pagesizes in each of its memory regions. This patch reports the pagesize > backing the VMA in /proc/pid/smaps. This should not break any sensible > parser as the file format is multi-line and it should skip information it > does not recognise. Time to play devil's advocate. :) To be fair, this doesn't return the MMU pagesize backing the VMA. It returns pagesize that hugetlb reports *or* the kernel's base PAGE_SIZE. The ppc64 case where we have a 64k PAGE_SIZE, but no hardware 64k support means that we'll have a 4k MMU pagesize that we're pretending is a 64k MMU page. That might confuse someone seeing 16x the number of TLB misses they expect. This also doesn't work if, in the future, we get multiple page sizes mapped under one VMA. But, I guess that all only matters if you worry about how the kernel is treating the pages vs. the MMU hardware. -- 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/ . Don't email: email@kvack.org