This is a discussion on Re: RELENG_7: interrupt eating whole cpu core - FreeBSD ; Tom Evans wrote: > On Fri, 2008-02-08 at 19:35 +0100, Dominic Fandrey wrote: >> Tom Evans wrote: >>> On Fri, 2008-02-08 at 17:14 +0100, Dominic Fandrey wrote: >>>> Tom Evans wrote: >>>>> If I try to turn on DMA, I ...
Tom Evans wrote:
> On Fri, 2008-02-08 at 19:35 +0100, Dominic Fandrey wrote:
>> Tom Evans wrote:
>>> On Fri, 2008-02-08 at 17:14 +0100, Dominic Fandrey wrote:
>>>> Tom Evans wrote:
>>>>> If I try to turn on DMA, I just get WDMA2, which just doesn't cut it:
>>>> I think any DMA mode is fast enough to handle a DVD drive. There's just no
>>>> necessity for more.
>>> WDMA is not UDMA. Any UDMA variant would be enough. WDMA2 provides a
>>> maximum of 16MiB/s, which will frequently lead to buffer underruns
>>> viewing a DVD. UDMA2 provides a maximum of 33MiB/s, which IS plenty.
>> 16MB/s is exactly what is needed for 12x DVD access. I think this is the usual
>> speed for a Notebook drive nowadays and it suffices for me.
>>>>>> # atacontrol mode acd0 udma5
>>>>> current mode = WDMA2
>>>> Same as for me. I'm satisfied with the speed of the drive.
>>> I'm rarely satisfied - I'm quite often not bothered enough to pursue
>> Well, if 12x speed is not enough for you, you have to use an external drive.
>> This is not a driver issue. It's just what your drive supports.
> The chipset supports UDMA6, the drive supports UDMA6, I should be happy
> with WDMA2 because 'thats what works'? Thanks for your 'help'. I'll
> continue on here from myself.
I don't know which drive you are using, but mine even only supports
8xDVD-reading so the highest transfer rate is 9.9606 MB/s. There's no way a
faster mode would improve anything.
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