linux-kernel - Re: Boot time regression in 2.6.38 after initial wq merge

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Date:	Tue, 22 Feb 2011 09:59:55 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	"pantherchen@...sanet.de" <pantherchen@...sanet.de>
Cc:	Tejun Heo <tj@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Boot time regression in 2.6.38 after initial wq merge

On Tue, Feb 22, 2011 at 09:22:54AM -0800, Dmitry Torokhov wrote:
> On Tue, Feb 22, 2011 at 04:04:02PM +0100, pantherchen@...sanet.de wrote:
> > On 02/22/2011 10:15 AM, Dmitry Torokhov wrote:
> > >I'd like to see rc6 tried.
> > 
> > Unfortunately it shows the same behavior [0]. (To speed things up, I
> > used a stripped down kernel config [1], while the first two posted
> > boot charts used Ubuntu's stock kernels.)
> > 
> > I was surprised that the kernel directly built from the wq branch
> > and the last "good" kernel from Linus' tree with the 33 patches
> > applied don't show the increased boot time - shouldn't they all be
> > the same?
> > 
> 
> No, because there were more merges between your last-known-good (which
> is somewhere in the middle of Jiri's HID merge) and Tejun's workqueue
> pull. Namely there was merge of my tree that changed serio from using
> kseriod to the common workqueue.
> 
> Just to confirm, if you revert commit
> 
> 	8ee294cd9def0004887da7f44b80563493b0a097
> 
> from 2.6.38-rc6, does this restore boot time?
> 

And if that indeed fixes the issue I wonder if the reason for the stall
is that we trip on flush_scheduled_work() somewhere. If you could stick
dump_stack() into flush_scheduled_work() that might give us some clues.

Thanks.

-- 
Dmitry
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