Subject: Re: [patch] drivers: wait for threaded probes between initcall
	levels
From: Xavier Bestel <xavier.bestel@free.fr>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Kyle Moffett <mrmacman_g4@mac.com>, Linus Torvalds <torvalds@osdl.org>,
       "Adam J. Richter" <adam@yggdrasil.com>, akpm@osdl.org, bunk@stusta.de,
       greg@kroah.com, linux-kernel@vger.kernel.org,
       linux-pci@atrey.karlin.mff.cuni.cz, matthew@wil.cx, pavel@ucw.cz,
       shemminger@osdl.org
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Date: Mon, 30 Oct 2006 16:28:35 +0100
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On Mon, 2006-10-30 at 16:05 +0100, Arjan van de Ven wrote:
> On Mon, 2006-10-30 at 16:00 +0100, Xavier Bestel wrote:
> > On Mon, 2006-10-30 at 15:38 +0100, Arjan van de Ven wrote:
> > 
> > > how much of this complexity goes away if you consider the
> > > scanning/probing as a series of "work elements", and you end up with a
> > > queue of work elements that threads can pull work off one at a time (so
> > > that if one element blocks the others just continue to flow). If you
> > > then find, say, a new PCI bus you just put another work element to
> > > process it at the end of the queue, or you process it synchronously. Etc
> > > etc.
> > > 
> > > All you need to scale then is the number of worker threads on the
> > > system, which should be relatively easy to size....
> > > (check every X miliseconds if there are more than X outstanding work
> > > elements, if there are, spawn one new worker thread if the total number
> > > of worker threads is less than the system wide max. Worker threads die
> > > if they have nothing to do for more than Y miliseconds)
> > 
> > Instead of checking every X ms, just check at each job insertion.
> 
> that would lead to a too eager amount of threads if processing the jobs
> is really really quick ...

Don't you have a "no more than X threads at once" limit ? You just
*check* at job insertion, not unconditionnaly fork.

	Xav

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