[rescue] Sun 711

[Chris Byrne]

No he's right, interrupts will kill you even if its doing a single task. x86
mobos suck that wasy. Try it and you'll see. There WILL be a significant
portion of unrelated interrupts, and they WILL take a small but measurable
amount of time away from the I/O. That's why you really need big cache on
these controllers.

It may not make logical sense (actually it does if you go into way too much
detail for this discussion) but believe me I've done the testing. On the
whole x86 mobo interrupt management and latency suck as does their DMA
management.

100 to 125MB/s is easy, anything more than that and it starts to get hard.
Getting to around 250 MB/s shouldnt be all that diffiult with a single 64/66
bus, but to have sustained throughput more than that you really do need two
busses.

Chris Byrne

> -----Original Message-----
> From: rescue-admin at sunhelp.org [mailto:rescue-admin at sunhelp.org]On
> Behalf Of David Passmore
> Sent: 02 May 2002 17:16
> To: rescue at sunhelp.org
> Subject: Re: [rescue] Sun 711
>
>
> On Thu, May 02, 2002 at 07:40:56AM -0700, James Lockwood wrote:
>
> > 100MB/s is easy.  300MB/s is not.  300MB/s both to disk and video is
> > really not.  You not only need big I/O cajones, but you are
> stressing main
> > RAM bandwidth in a significant way.  Fast CPU cache will do nothing for
> > you here.  Interrupts will kill you if you're not careful.
>
> Take a look at how fast the bus and memory bandwidths are on the latest
> Pentium IV motherboards with RDRAM. Sure, it's the same old bus, but the
> clocks have been ratcheted up to insane (well, relative to what
> they were a
> couple of years ago) levels. You don't need a crossbar switch for this
> simple task.
>
> Interrupts will kill you? Interrupts from what? We're not talking about a
> multi-purpose machine here. There's a single task running, the machine is
> probably doing a lot of DMA transfers across the bus, and that's about it.
>
> David
> _______________________________________________
> rescue list - http://www.sunhelp.org/mailman/listinfo/rescue