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From: Yep on 18 Jun 2008 21:58
Martin Etteldorf wrote:
> What about sysctl hw.ata.atapi_dma?
> I assume it's set to "1". If that's the case, try setting it to "0".

Wouldnt this make drive access nice and slow, PIO data transfers require
a significant amount of CPU time too and give about 1/10th of the
throughput?

I have had this problem too on a couple of machines (intel based chipsets).

I'd say its more a driver issue than hardware, especially if other
operating systems are able to utilize the DMA with no issue on the same
machine.
From: Martin Etteldorf on 19 Jun 2008 00:00
Yep <yep(a)yep> wrote:
> Martin Etteldorf wrote:
>> What about sysctl hw.ata.atapi_dma?
>> I assume it's set to "1". If that's the case, try setting it to "0".
>
> Wouldnt this make drive access nice and slow, PIO data transfers require
> a significant amount of CPU time too and give about 1/10th of the
> throughput?

No, it wouldn't.


Martin
--
"For the Snark's a peculiar creature, that won't
Be caught in a commonplace way.
Do all that you know, and try all that you don't;
Not a chance must be wasted to-day!"
From: Yep on 19 Jun 2008 11:09
Martin Etteldorf wrote:
> Yep <yep(a)yep> wrote:
>> Martin Etteldorf wrote:
>>> What about sysctl hw.ata.atapi_dma?
>>> I assume it's set to "1". If that's the case, try setting it to "0".
>> Wouldnt this make drive access nice and slow, PIO data transfers require
>> a significant amount of CPU time too and give about 1/10th of the
>> throughput?
>
> No, it wouldn't.
>
>
> Martin

So lets break this down, disabling DMA means that PIO data transfers are
used right? So, you are disagreeing that PIO is slower that DMA mode
transfers?
From: Michael Sierchio on 19 Jun 2008 11:45
Yep wrote:
> Martin Etteldorf wrote:
>> Yep <yep(a)yep> wrote:
>>> Martin Etteldorf wrote:
>>>> What about sysctl hw.ata.atapi_dma?
>>>> I assume it's set to "1". If that's the case, try setting it to "0".
>>> Wouldnt this make drive access nice and slow, PIO data transfers
>>> require a significant amount of CPU time too and give about 1/10th of
>>> the throughput?
>>
>> No, it wouldn't.
>>
>>
>> Martin
>
> So lets break this down, disabling DMA means that PIO data transfers are
> used right? So, you are disagreeing that PIO is slower that DMA mode
> transfers?

The assertion of 1/10th the throughput is absurd, and gives reason
enough to refute the assertion.

From: jpd on 19 Jun 2008 11:49
On Thu, 19 Jun 2008 08:45:59 -0700,
Michael Sierchio <kudzu-usenet2(a)tenebras.com> wrote:
> Yep wrote:
>> So lets break this down, disabling DMA means that PIO data transfers
>> are used right? So, you are disagreeing that PIO is slower that DMA
>> mode transfers?
>
> The assertion of 1/10th the throughput is absurd, and gives reason
> enough to refute the assertion.

Well, don't forget to do so. While at it, provide some numbers.


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