[Soekris] Harddisk Slow

[Ron Watkins]

As far as I know, we just covered this two or three weeks ago.  
According to what others said, the DMA lines on early 4801s are not 
connected.  Only PIO mode works.  It's claimed that the latest versions 
have connected those pins and now function in DMA mode.   I haven't 
worked with these newer models, but can definitely confirm that my old 
4801 will not do DMA. 

I realize that this sounds like a dumb design mistake, but when the 4801 
was introduced, CF cards were PIO-only, and there were problems, big 
problems, if you tried to use them at higher speeds.  Setting the system 
to be PIO was the safest choice at the time.  Remember, the 4801 is 
ancient hardware; the design is about 4 years old.   It's extremely 
robust, mind, and a very good device, just... it was created a long time 
ago.  PIO-only was not stupid at the time.  :)

If you have an old 4801 and want to do DMA, you're probably going to 
have to buy new hardware.... either a new unit, or a DMA-capable IDE 
controller for the PCI slot.  If you opt for a new unit, please verify 
with Soekris that the new 4801s will do what you need, as I have not 
tested them.

Igor Sobrado wrote:
> In message <20070131105543.GB1800 at mathom.us>, Michael Stone writes:
>   
>> On Wed, Jan 31, 2007 at 10:21:04AM +0100, Igor Sobrado wrote:
>>     
>>> bs is the block size, not the buffer size.  It is, however, an useless
>>> parameter if the filesystem is not tuned to use that block size on all
>>> transactions by means of newfs.  
>>>       
>> It's not useless, as the numbers provided by the person you're replying 
>> to show. A meg is overkill, but but it obviously was better than 512b. 
>>     
>
> Hi Mike.
>
> A block size of 1MB means that the even small scripts (e.g., a 600 bytes
> shell script) will require 128KB to be stored.  Indeed, larger block
> sizes show that the IDE controller is not the bottleneck on these
> appliances.  I am just curious: if these drives are working in advanced
> DMA modes (in most cases, UltraDMA 2) why is the interrupt load so high?
>
> I am using a PowerEdge 350 here.  It can easily provide 20MB/s with
> an 800MHz PIII procesor.  The net4801 has a relatively fast Geode
> processor (266 MHz is not too slow).  Even my 400MHz PII laptop
> is faster than the net4801 in both writing and reading:
>
> $ dd if=/dev/zero of=test count=65536 
> 65536+0 records in
> 65536+0 records out
> 33554432 bytes transferred in 2.833 secs (11844134 bytes/sec)
>
> $ dd if=test of=/dev/null count=65536
> 65536+0 records in
> 65536+0 records out
> 33554432 bytes transferred in 1.242 secs (27016450 bytes/sec)
>
> Perhaps an interrupt routing problem on the net4801?  If there is
> an interrupt routing problem, there is a hope this problem being
> fixed in a future firmware upgrade, concurrently to the integer
> overflow problem described in a previous post.
>
> Best wishes,
> Igor.
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