Re: How to determine performance bottleneck?

[Tejun Heo <tj@kernel.org>]

Pierre Ossman wrote:
> On Tue, 14 Oct 2008 08:25:22 +0900
> Tejun Heo <tj@kernel.org> wrote:
> 
>> Pierre Ossman wrote:
>>> When I'm accessing a single disk, the bandwidth is 70 - 80 MiB/s. When
>>> I access a second disk, the bandwidth is about 50 MiB/s/disk, and all
>>> five results in 25 MiB/s/disk. In other words, something is limiting
>>> things to about 100 MiB/s. Now the question is what that limiting
>>> factor is.
>>>
>> That's the limit of sil3124/3132.  Dunno why but you can't go over that.
> 
> Bummer. Is this per port, or is it the PCIe side of the chip that is
> limited to this speed?

I think it's on the host bus side.

> What do the silicon image guys have to say about it?

ISTR they confirmed the problem but I don't remember talking too much
about it.

>>  There's 3132-2 chip on the market.  Maybe it's worth a try?
>
> Now that model number was not something that was easily found on
> google, nor on silicon image's website. Know of any boards with that
> chip?

Somebody wrote me an email about it.  Looking up... eh.. can't find.  Sorry.

-- 
tejun