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Date: Thu, 12 Jul 2001 01:43:28 +0530
From: Dipankar Sarma <dipankar@sequent.com>
To: Jens Axboe <axboe@suse.de>
Cc: mike.anderson@us.ibm.com, linux-kernel@vger.kernel.org
Subject: Re: io_request_lock patch?
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In-Reply-To: <20010711212022.H712@suse.de>; from axboe@suse.de on Wed, Jul 11, 2001 at 09:20:22PM +0200
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On Wed, Jul 11, 2001 at 09:20:22PM +0200, Jens Axboe wrote:
> True. In theory it would be possible to do request slot stealing from
> idle queues, in fact it's doable without adding any additional overhead
> to struct request. I did discuss this with [someone, forgot who] last
> year, when the per-queue slots where introduced.
> 
> I'm not sure I want to do this though. If you have lots of disks, then
> yes there will be some wastage if they are idle. IMO that's ok. What's
> not ok and what I do want to fix is that slower devices get just as many
> slots as a 15K disk for instance. For, say, floppy or CDROM devices we
> really don't need to waste that much RAM. This will change for 2.5, not
> before.

Unless there is some serious evidence substantiating the need for
stealing request slots from other devices to avoid starvation, it
makes sense to avoid it and go for a simpler scheme. I suspect that device
type based slot allocation should just suffice.

Thanks
Dipankar
-- 
Dipankar Sarma  <dipankar@sequent.com> Project: http://lse.sourceforge.net
Linux Technology Center, IBM Software Lab, Bangalore, India.
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