From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755210Ab1ACO1j (ORCPT ); Mon, 3 Jan 2011 09:27:39 -0500 Received: from mail-bw0-f46.google.com ([209.85.214.46]:46187 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754191Ab1ACO1i (ORCPT ); Mon, 3 Jan 2011 09:27:38 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=QHtA4HSeEXexnYv460bTlSi9GkLBrvDW2+mlwNc/dD9O4hu+1HP/WzuRgovHzOE/IA hnBCkeE3igqL2afIGVqBnWkRCfVzXZ+kCsWPxY+GolRM9mCYKML5YKfq2HsehKUMYNch QmtaHwDk7nLV+9O8UtwShJTQBXi+6Zh/GstFs= Date: Mon, 3 Jan 2011 15:27:34 +0100 From: Tejun Heo To: Steven Whitehouse Cc: linux-kernel@vger.kernel.org, Christine Caulfield , David Teigland , cluster-devel@redhat.com Subject: Re: [PATCH 24/32] dlm: dlm workqueues aren't used in memory reclaim path Message-ID: <20110103142734.GR18831@htj.dyndns.org> References: <1294062595-30097-1-git-send-email-tj@kernel.org> <1294062595-30097-25-git-send-email-tj@kernel.org> <1294063107.2429.34.camel@dolmen> <20110103140107.GP18831@htj.dyndns.org> <1294064489.2429.58.camel@dolmen> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1294064489.2429.58.camel@dolmen> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello again, On Mon, Jan 03, 2011 at 02:21:29PM +0000, Steven Whitehouse wrote: > > Ooh, I see. Hmmm... maybe I've asked this before but do you really > > need WQ_MEM_RECLAIM there? Is dlm used during memory reclaim? > > Yes, it is in case of deallocation of inodes, so we have to be careful > about that, I see. I'm still slightly unsure about the WQ_MEM_RECLAIM rules when it comes to distributed file systems and stuff related to them, but I think it basically comes down to whether the code can be in the swap path or not. e.g. for nfs backed write shared mapped files, nfs definitely can be used during memory reclaim _but_ it's not guaranteed to make forward progress under memory pressure and thus can't be depended upon and shouldn't be used for swap. IOW, it may free memory but it's not in the critical path which should guarantee forward progress. Isn't dlm the same case? Thank you. -- tejun