linux-kernel - Re: Questions about Linux workqueue in 2.6.36

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Message-ID: <20110214130300.GH18742@htj.dyndns.org>
Date:	Mon, 14 Feb 2011 14:03:00 +0100
From:	Tejun Heo <tj@...nel.org>
To:	Ray Jui <rjui@...adcom.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Questions about Linux workqueue in 2.6.36

Hello,

On Wed, Feb 09, 2011 at 02:38:36PM -0800, Ray Jui wrote:
> You are right. The problem with the rescuer is that when it is
> leaving a gcwq, it does not check to see whether it needs to wake up
> a worker to process subsequent work items. After applying your
> patch, I see pid 26 getting waken up by the rescuer and work items
> from mmc1 and mmc2 are now being processed properly.

Cool, I'll send the patch to upstream and stable.

> I also did a quick profiling on the amount of time it takes to
> create a new worker on our system. It takes 15 ~ 20 ms. This is not
> surprising as it's an embedded system and it was during kernel boot
> up and the system was getting quite busy. Regardless, the current 10
> ms initial mayday timeout has resolution issues on a lot of embedded
> systems with worse timer resolutions (e.g., 10 ms on our system).

Can you please verify the second patch removes the unncessary rescuer
invocation?

Thanks.

-- 
tejun
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