Re: 2.5.69, IDE TCQ can't be enabled

Jens Axboe (axboe@suse.de)
Mon, 12 May 2003 20:59:34 +0200

On Mon, May 12 2003, Mudama, Eric wrote:
>
> The only difference between SATA TCQ and PATA TCQ is that in PATA TCQ, the
> drive doesn't report the active tag bitmap back to the host after each
> command. Other than that they are functionally identical to my
> understanding. (Yes, there are options like first-party DMA, but these are
> not requirements)

You are ignoring the host side of things. PATA TCQ is basically
unsupportable without some hardware support (auto-poll). It's my
understanding that all SATA controllers do that.

Then there's the debate of whether TCQ is worth it at all, in general. I
feel that a few tags just to minimize the time spent when ending a
request to starting a new one is nice.

> Personally I'd like to see the option stay in there as experimental, it
> helps us drive folks test stuff when we can just flip an option off/on to
> get that functionality.

I agree, besides it just needs a bit of fixing, can't be much.

-- 
Jens Axboe


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