linux-kernel - Re: [PATCH 1/4] fastboot: Asynchronous function calls to speed up kernel boot

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Message-ID: <20090104194946.GB496@one.firstfloor.org>
Date:	Sun, 4 Jan 2009 20:49:46 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	Andi Kleen <andi@...stfloor.org>, linux-kernel@...r.kernel.org,
	torvalds@...ux-foundation.org, mingo@...e.hu, fweisbec@...il.com,
	linux-scsi@...r.kernel.org, linux-ide@...r.kernel.org,
	linux-acpi@...r.kernel.org, akpm@...ux-foundation.org
Subject: Re: [PATCH 1/4] fastboot: Asynchronous function calls to speed up kernel boot

On Sun, Jan 04, 2009 at 11:09:32AM -0800, Arjan van de Ven wrote:
> On Sun, 04 Jan 2009 20:05:26 +0100
> Andi Kleen <andi@...stfloor.org> wrote:
> 
> > Surely the thread should die again boot up? On module load
> > synchronisity is usually not a problem.
> 
> sadly that's not correct in practice based on the fast boot work we've
> done.

Hmm, but I'm not sure your current code is module safe, in particular 
against unloading again. You would likely need a barrier at the end
of module load at least.

> 
> > 
> > Personally I think it would be better to make this more generic.
> > Various subsystems have thread pool implementations now, 
> 
> sort of kinda. If a good one appears I'd be happy to build on top of
> that, assuming it's generic enough.

I think you can just create a separate barrier primitive which
will work independently of any special thread managers.

> 
> > and this
> > is just another variant that except for the sequence stuff
> > isn't all that much different. So it would be better to have 
> > a generic worker thread manager that just supports these
> > barriers too.
> 
> ... or maybe think about seeing this system as exactly that thread
> manager?

I'm not sure it's generic enough.

-Andi

-- 
ak@...ux.intel.com
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