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From: David Howells <dhowells@redhat.com>
In-Reply-To: <1254384558-1018-20-git-send-email-tj@kernel.org>
References: <1254384558-1018-20-git-send-email-tj@kernel.org> <1254384558-1018-1-git-send-email-tj@kernel.org>
To: Tejun Heo <tj@kernel.org>
Cc: dhowells@redhat.com, jeff@garzik.org, mingo@elte.hu,
       linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
       jens.axboe@oracle.com, rusty@rustcorp.com.au, cl@linux-foundation.org,
       arjan@linux.intel.com
Subject: Re: [PATCH 19/19] workqueue: implement concurrency managed workqueue
Date: Thu, 01 Oct 2009 14:15:26 +0100
Message-ID: <10231.1254402926@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1077
Lines: 22

Tejun Heo <tj@kernel.org> wrote:

> gcwq always keeps at least single idle worker around.  When a new
> worker is necessary and the worker is the last idle one, the worker
> assumes the role of "manager" and manages the worker pool -
> ie. creates another worker.  Forward-progress is guaranteed by having
> dedicated rescue workers for workqueues which may be necessary while
> creating a new worker.  When the manager is having problem creating a
> new worker, mayday timer activates and rescue workers are summoned to
> the cpu and execute works which may be necessary to create new
> workers.

I take it that means that the rescue-workers are donated to the pool to become
worker threads (perhaps on a temporary basis) in the event that forking fails
due to ENOMEM, such that resources can be freed up for fork() to use.

David
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