From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay1.corp.sgi.com [137.38.102.111]) by oss.sgi.com (Postfix) with ESMTP id 0A0987F37 for ; Mon, 12 Oct 2015 19:23:54 -0500 (CDT) Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by relay1.corp.sgi.com (Postfix) with ESMTP id EC4268F8035 for ; Mon, 12 Oct 2015 17:23:50 -0700 (PDT) Received: from ipmail04.adl6.internode.on.net (ipmail04.adl6.internode.on.net [150.101.137.141]) by cuda.sgi.com with ESMTP id AiDdeHQLmTPYG7Y4 for ; Mon, 12 Oct 2015 17:23:47 -0700 (PDT) Date: Tue, 13 Oct 2015 11:23:08 +1100 From: Dave Chinner Subject: Re: mkfs.xfs -n size=65536 Message-ID: <20151013002308.GI27164@dastard> References: <0F279340237AA148AD7E3C6A70561A5E01266BE7@xmb-rcd-x14.cisco.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <0F279340237AA148AD7E3C6A70561A5E01266BE7@xmb-rcd-x14.cisco.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: "Al Lau (alau2)" Cc: "xfs@oss.sgi.com" On Fri, Oct 09, 2015 at 10:40:00PM +0000, Al Lau (alau2) wrote: > I am looking for more details on the "-n size=65536" option in > mkfs.xfs. The question is the memory allocation this option > generates. The system is Redhat EL 7.0 > (3.10.0-229.1.2.el7.x86_64). > > We have been getting this memory allocation deadlock message in > the /var/log/messages file. The file system is used for ceph OSD > and it has about 531894 files. So, if you only have half a million files being stored, why would you optimised the directory structure for tens of millions of files in a single directory? > Oct 6 07:11:09 abc-ceph1-xyz kernel: XFS: possible memory allocation deadlock in kmem_alloc (mode:0x8250) mode = ___GFP_WAIT | ___GFP_IO | ___GFP_NOWARN | ___GFP_ZERO = GFP_NOFS | GFP_ZERO | GFP_NOWARN which means it's come through kmem_zalloc() and so is a heap allocation and hence probably quite small. Hence I doubt that has anything to do with the directory block size, as the directory blocks are allocated as single pages through a completely allocation different path and them virtually mapped... Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs