linux-kernel - Re: [PATCH 4/7] libata: use lazy workqueues for the pio task

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Message-ID: <4A92C500.4030109@garzik.org>
Date:	Mon, 24 Aug 2009 12:51:12 -0400
From:	Jeff Garzik <jeff@...zik.org>
To:	Jens Axboe <jens.axboe@...cle.com>
CC:	linux-kernel@...r.kernel.org, benh@...nel.crashing.org,
	htejun@...il.com, bzolnier@...il.com, alan@...rguk.ukuu.org.uk,
	akpm@...ux-foundation.org
Subject: Re: [PATCH 4/7] libata: use lazy workqueues for the pio task

On 08/24/2009 12:42 PM, Jens Axboe wrote:
> On Mon, Aug 24 2009, Jeff Garzik wrote:
>> No objections to the code, operationally...
>>
>> But it is disappointing that the "1 thread on UP" problem is not solved
>> while changing this libata area.  Is there no way to specify a minimum
>> lazy-thread count?
>>
>> A key problem continues to be tying to the number of CPUs, which is
>> quite inappropriate for libata.
>
> We'll solve that next, the first problem is reducing the per-cpu
> threads. Lots of places use per-cpu workqueues because that is what is
> available, not necessarily because it's an appropriate choice. Like the
> ata_wq above, it's not even a good fit.

Agreed + sounds great.

Thanks -- both for hacking libata for this, and more generally, for 
attacking the too-many-kthreads problem!  :)  It's just sad how many 
unused workqueue threads hang about, on every modern Linux box.

	Jeff



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