Subject: Re: SMPs - clusters - db perf. - parallelism

From: [email-masked]
Date: Sun, 25 Apr 1999 19:25:08 -0500

Saleh,

Sorry, I don't have any direct pointers for you on that topic. But I can
give you some indirections.

I doubt there are any journal articles and the like. I would look on the
web sites of database vendors (Oracle, Sybase, DB2 (for 390 and for other
systemss -- two different programs, one name (marketing!)), Informix,
Tandem/Compaq). What I'd look for are white papers, "red books" (IBM), and
other things attempting to educate programmers on how to write SQL that
runs well in parallel.

There *might* also be some information on the web sites of system vendors
who do parallel commercial systems (IBM, HP, Sun, Compaq/DEC,
Compaq/Tandem), but you're more likely to find it on the database vendors'
sites, I think.

And hey, if you find anything interesting and/or useful, let me know.

I agree with you that it is a key attribute. It's not the only one,
obviously -- making parallelism work is a large logical "AND": One thing
doesn't work and it doesn't work.

Greg Pfister
Senior Technical Staff Member, IBM Advanced Technology & Architecture,
Server Design
(512) 838-8338 | IBM tieline 678-8338 | FAX (512) 838-3418        Sic
Crustulum Frangitur

---

From: [email-masked]
Date: Sun, 9 May 1999 15:33:53 -0500

Saleh,

You're welcome. Your questions --

> A bit surprised at example one though; I thought Sun conducted
> an OLTP benchmark (TPC-C) few months ago on the 64-way SMP.
> I recall coming across and announcement from them sometimes
> toward the end of last year.

Yes, they finally did it. That was about 18 months (or so) after the system
started shipping. Others like to have TPC-C numbers available on the day it
first officially ships -- "general availability." The point is that they
couldn't, because the software just wasn't there. For a good 18 months their
highest TPC-C rating was on a system that wasn't their biggest.

>> (1) Locality will become ever-increasingly important; even communicating to
the
>> other side of a chip will have a performance cost in 6-7 years.
>
> Giving the current high emphasis on various issues of performance, I'd go
> as far as halfing that number, to around 4 years or so.

Might not be a bad number.

>> Implication:
>> Every large SMP will inevitably be NUMA.
>

>But do you believe that 'N' of cc-NUMA will come close to 1:1 ratio or
>something of the neighbourhood within those number of years? That
>will be one ideal thing to have but with that, is the model will still
>be coined 'NUMA'?

Everybody's saying that in their soon-to-be-announced system they'll do NUMA
"right" -- as opposed to those horrid 7.5:1 ratios (on a good day with the wind
at your back going downhill) that the first generation has, except for SGI. I
think "right" will actually turn out to be 3-4:1 (under the same conditions).
That's lots better, but it's still explicitly NUMA.

Ultimately -- yes, I think it will be large enough to be explicitly NUMA on a
single chip, meaning 3:1 or more. But I think the metric will change. It will be
more a measure of the ratio of access for some depth of cache -- since caches
are going to get so big they'll be where virtually all the data references come
from. Except for those old scientific codes that stream data from memory, of
course.

Greg Pfister
Senior Technical Staff Member, IBM Advanced Technology & Architecture, Server
Design
(512) 838-8338 | IBM tieline 678-8338 | FAX (512) 838-3418        Sic Crustulum
Frangitur

---

From: [email-masked]
Date: Fri, 4 Jun 1999 15:57:32 -0500

Saleh,

Thanks, but when I try to open that URL I can't resolve that host name -- and
trying the obvious (www.neci.com) gets an odd error (something about virtual
directory) and a "not found" for http://www.neci.com/isca99/ and =/index.html.

Greg Pfister
Senior Technical Staff Member
IBM Advanced Technology & Architecture, Server Design
(512) 838-8338 | IBM tieline 678-8338 | FAX (512) 838-3418
Sic Crustulum Frangitur

To:   Greg Pfister/Austin/IBM@IBMUS
cc:
Subject:  Re: SMPs - clusters - db perf. - parallelism

Hi Greg,

been a while since my last email :-)

On the implication of HW on SW design or rather having
HW get way ahead of the SW, you might interested in some
of the bits presented by SGI's Steve Oberlin at
ISCA'99:

http://www.neci.nec.com/isca99/index.html

-Saleh