Re: kernel 2.6.31.1 + Sil 3512 + WDC WD5000AAKS-00V1A0 = no NCQ and UDMA5 instead of UDMA6

[Robert Hancock <hancockrwd@gmail.com>]

On 12/17/2009 09:49 PM, Stan Hoeppner wrote:
> Jeff Garzik put forth on 12/17/2009 9:10 PM:
>
>> Nope.  You are pretty much maxing out the drive, of whatever drive you
>> plug in.  The sata bus -- at its hardware spec'd maximum -- is far
>> faster than just about any drive, and the PCI bus is far faster than the
>> sata bus.
>
> I'm on the old 32bit/33MHz PCI bus of 133MB/s.  SATA1 at 150MB/s is
> slightly faster, no?  No argument here that both are far faster than
> almost all drives on the market.  I was just wondering if bumping up
> from the default UDMA/100 to UDMA/133 would allow quicker PCI bus
> bursting and thus a slight improvement in overall performance.

The UDMA speed doesn't make any difference at all with SATA, it's just 
an arbitrary number in almost all cases. Only the link speed really 
matters (which with these controllers will always be 1.5 Gbps).

>
>> You could probably max out the SATA bus with a RAM-based SATA device;
>> that's it.
>
> Yeah, I've seen some results published of quality SSDs and they just
> absolutely scream in latency, IOPs, and throughput.  That's not in my
> future, it's complete overkill for my applications, performance and
> dollar wise.  I just want to optimize the performance of what I already
> have.
>
> I think I only gave $15 for this Koutech Sil3512 PCI (32/33) controller
> at Newegg.  You being you with the knowledge you have, would buying one
> of the cards whose chipset supports NCQ, such as the sata_sil24 cards,
> be anything close to worth the additional investment in dollars and time
> spent swapping hardware and drivers?  Is NCQ the performance panacea
> that some purport it to be?  How much difference does it really make?

It's really hard to say, it depends on the drive and the workload, in 
most cases..