From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754249AbcEaVBT (ORCPT ); Tue, 31 May 2016 17:01:19 -0400 Received: from mail-yw0-f176.google.com ([209.85.161.176]:35076 "EHLO mail-yw0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750813AbcEaVBS (ORCPT ); Tue, 31 May 2016 17:01:18 -0400 Date: Tue, 31 May 2016 17:01:16 -0400 From: Tejun Heo To: Keith Busch Cc: linux-mm@kvack.org, LKML Subject: Re: [PATCH] mm/swap: lru drain on memory reclaim workqueue Message-ID: <20160531210116.GA14868@mtj.duckdns.org> References: <1464727815-13073-1-git-send-email-keith.busch@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1464727815-13073-1-git-send-email-keith.busch@intel.com> User-Agent: Mutt/1.6.1 (2016-04-27) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 31, 2016 at 02:50:15PM -0600, Keith Busch wrote: > + system_mem_wq = alloc_workqueue("events_mem_unbound", WQ_UNBOUND | WQ_MEM_RECLAIM, So, WQ_MEM_RECLAIM on a shared workqueue doesn't make much sense. That flag guarantees single concurrency level to the workqueue. How would multiple users of a shared workqueue coordinate around that? What prevents one events_mem_unbound user from depending on, say, draining lru? If lru draining requires a rescuer to guarantee forward progress under memory pressure, that rescuer worker must be dedicated for that purpose and can't be shared. Thanks. -- tejun