Re: [patch 2.6.15-rc2] blk: request poisoning

[Nick Piggin <nickpiggin@yahoo.com.au>]

Jens Axboe wrote:
> On Mon, Nov 21 2005, Nick Piggin wrote:
> 
>>This patch should make request poisoning more useful
>>and more easily extendible in the block layer.
>>
>>Don't think I have hardware that will trigger a requeue,
>>but otherwise it has been moderately tested. Comments?
> 
> 
> I like the idea, but I'm a little worried that it actually introduces
> more problems than it solves. See the mail from yesterday for instance,
> perfectly fine code but 'as' poisoning triggered.
> 
> And the merging bits already look really ugly :/
> 
> So I guess my question is, did this code ever find any driver problems?
> 

I think it found a few things here and there. Requeueing had a
couple of bugs, and I think a couple of things turned up back when
AS was a new concept to the block layer.

I think it is useful to try to enforce a coherent usage of the block
interface by drivers. For example, the IDE thing may have been a non
issue, but you might imagine some io scheduler or future accounting
(or something) in the block layer actually does need the request to
go through elv_set_request / blk_init_request.

Up to you really. I'm going to rip the code out of as-iosched.c so
I just thought it may still be useful for the block layer.

Thanks,
Nick

-- 
SUSE Labs, Novell Inc.

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