From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f49.google.com (mail-oi0-f49.google.com [209.85.218.49]) by kanga.kvack.org (Postfix) with ESMTP id 22DC76B0255 for ; Thu, 22 Oct 2015 10:41:15 -0400 (EDT) Received: by oifu63 with SMTP id u63so5730020oif.2 for ; Thu, 22 Oct 2015 07:41:14 -0700 (PDT) Received: from resqmta-ch2-07v.sys.comcast.net (resqmta-ch2-07v.sys.comcast.net. [2001:558:fe21:29:69:252:207:39]) by mx.google.com with ESMTPS id y128si8938575oig.67.2015.10.22.07.41.14 for (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Thu, 22 Oct 2015 07:41:14 -0700 (PDT) Date: Thu, 22 Oct 2015 09:41:11 -0500 (CDT) From: Christoph Lameter Subject: Re: [PATCH] mm,vmscan: Use accurate values for zone_reclaimable() checks In-Reply-To: <20151022143349.GD30579@mtj.duckdns.org> Message-ID: References: <20151021145505.GE8805@dhcp22.suse.cz> <201510222037.ACH86458.OFOLFtQFOHJSVM@I-love.SAKURA.ne.jp> <20151022140944.GA30579@mtj.duckdns.org> <20151022142155.GB30579@mtj.duckdns.org> <20151022142429.GC30579@mtj.duckdns.org> <20151022143349.GD30579@mtj.duckdns.org> Content-Type: text/plain; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Tejun Heo Cc: Tetsuo Handa , mhocko@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, David Rientjes , oleg@redhat.com, kwalker@redhat.com, akpm@linux-foundation.org, hannes@cmpxchg.org, vdavydov@parallels.com, skozina@redhat.com, mgorman@suse.de, riel@redhat.com On Thu, 22 Oct 2015, Tejun Heo wrote: > The only way to hang the execution for a work item w/ WQ_MEM_RECLAIM > is to create a cyclic dependency on another work item and keep that > work item busy wait. Workqueue thinks that work item is making > progress as it's running and doesn't schedule the next one. > > (I was misremembering here) HIGHPRI originally was implemented > head-queueing on the same pool followed by immediate execution, so > could get around cases where this could happen, but that got lost > while converting it to a separate pool. I can introduce another flag > to bypass concurrency management if necessary (it's kinda trivial) but > busy-waiting cyclic dependency is a pretty unusual thing. > > If this is actually a legit busy-waiting cyclic dependency, just let > me know. There is no dependency of the vmstat updater on anything. They can run anytime. If there is a dependency then its created by the kworker subsystem itself. -- 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