HPUX11v3 Hyper-threading

[Andre Braganca]

A rx2600 with 2 CPU 1.5GHz was replaced by a rx2620 with a dual-core 1.6GHz/18M. The internal disks, with HPUX 11.23, were moved from one server to the other. We saw no big improvement of performance.
Last month I went to a HPUX11v3 presentation and I think I heard something like "with this new version now hyperthreading is available". Could this be what it's missing to be able to use the dual-core to full performance ?

Regards,
André'
P.s. Don't know if it's against the "etiquette" but I've posted a similar question in the servers forum.

[Dennis Handly]

>Could this be what it's missing to be able to use the dual-core to full performance?

Dual-core is 2 CPUs. Hyperthreading can even be more but is a separate issue.

The answer is depends. Sometimes it helps sometimes it hurts.

>Don't know if it's against the "etiquette" but I've posted a similar question in the servers forum.

There is a lot of OS issues with it.
It helps if you included a link:
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=1115314

[Steven E. Protter]

Shalom,

I'm not surprised that the new Os further optimizes chips that were not in existance when the 11.23 release was released.

I'd hope you'd see a substantial performance bosot.

SEP

[Alzhy]

Andre - greetings.

It depends really on your application -- if it is multi-threaded - then it will certainly make use of the added CPU cores.

But if your applications are simply single threaded ones - then expect a very slight boost (that .1Ghz increase in clock speed will not matter). The added CPU cores' beenfit will manifest in being able to run concurrently about 2 more of your single-threaded applications...

What applications do you have that you expect a boost going from 2 cores to 4 cores?

[Hein van den Heuvel]

>> A rx2600 with 2 CPU 1.5GHz was replaced by a rx2620 with a dual-core 1.6GHz/18M.

Perhaps I am being dense here, but was that a SINGLE dual core, so the system still shows 2 HPUX-CPUS = 2 cores (now 1 chip) ?

>> The internal disks, with HPUX 11.23, were moved from one server to the other. We saw no big improvement of performance.

Well, you did not get mroe CPUs,
The CPU was only marginally faster,
The disk speed is exactly the same.
The only thing that really changed is a much large cache. That can offer a significant improvement IF (and only if) memory latency was the crititcal system component defining performance.
As you do not even mention memory, the suggestion is that memory (access) was not deemed critical.

So what was the 'bottleneck', best you know?! How did the chacnge address that bottleneck?

>> Last month I went to a HPUX11v3 presentation and I think I heard something like "with this new version now hyperthreading is available". Could this be what it's missing to be able to use the dual-core to full performance ?

NO. Dual core is always active.

Hpyerthreading is optional and out-of-the-box it is switch off, as the performance potential is highly dependend on the application. When you switch it on HPUX will see double the CPUs to play with, but your performance potential is more likely to be just 10% or so ( -10% to +40% range ).

Hope this helps some,
Hein van den Heuvel (at gmail dot com)
HvdH Performance Consulting

[Torsten.]

Hi,

hyperthreading is supported with 11.31 and the Montecito (not for 11.23 and previous CPUs) and the default is on, e.g.

# setboot
Primary bootpath : 0/0/1/1/0.0x0.0x0 (/dev/rdisk/disk13)
HA Alternate bootpath : 0/0/8/1/0.0x0.0x0 (/dev/rdisk/disk19)
Alternate bootpath : 0/0/1/1/1.0x2.0x0 (/dev/rdisk/disk18)

Autoboot is ON (enabled)
Hyperthreading : ON
: ON (next boot)

IMHO this will affect the performance.

[Andre Braganca]

Greetings Hein van den Heuvel,

If there is someone who is being a bit dense it's me ;-), because I'm trying to shortcut a few hours research on this "hyperthreading" subject! You're right, almost nothing changed. What just have an idea, origin unknown, that somehow the dual-core in one chip could be better for that hyperthingthreading. And I think Torsten is right on saying that the thing only works on 11v3.

It looks as if now I have to find out if my CPU intensive application (SAP BW data loading from backend system, on Oracle) can benefit from hyperthreading.

Regards,
Andre'

[Hein van den Heuvel · Accepted solution]

Hmmm, when I left HP almost 2 years ago, discussion were still raging on Hyperthreading, but they were leaning towards disable out of the box.
I guess Hyperthreading is enabled in Firmware, still not automatically in use by HPUX.

The best Document on this is probably:

http://docs.hp.com/en/setbootv3/setboot.pdf

Now for SAP specifically there is more data, but not all of it is shared :-(.
(Failures are rarely documented in this world)
Still, start with:
http://www.sap.com/solutions/benchmark/index.epx
There is BI data there, but not for Montecito best I can tell (please do correct me if i am wrong).
But let's switch to the 2-tier SD results and specifically: http://www.sap.com/solutions/benchmark/pdf/cert8906.pdf
and it reads:

"HP Integrity SD64B , 64 processors / 128 cores / 256 threads, Dual-Core Intel Itanium 2 9050"

You can bet your sweet ..., that if HP published with threads enabled, then they were of use.
However, I'm under the impression (chat at the bar :-) that they were only of limited use. It gave less than 10% benefit.

Please realize that a SAP solution on HP comes with a vast infrastucture. Folks in Walldorf Germany, Houston TX, Redmond CA, Nashua NH, and not in the least Cupertino, CA have extensive experience with this solution and should be able to advice you optimally when given a chance. (I shoudl know, I was one of them :^). Those folks do NOT troll the ITRC conference, but they do occasionally present at HP Tech Forums and the likes.

Hope this helps some,
Hein van den Heuvel (at gmail dot com)
HvdH Performance Consulting

[Hein van den Heuvel]

Argh, cut & paste error. That setboot document in helpful, but the better place to read up on all this is:

http://h71028.www7.hp.com/ERC/downloads/4AA0-7695ENW.pdf

Also, since you are concerned with the loading into Oracle, the TPC datapoints may have a better than average relevance for you.

Recently (2/27/2007) HP scored a TOP-1 absolute performance non-clustered result.

Again it was done with threads enabled.

(Of course that result was scored by very crafty folks tweaking the ... out of every setting imaginable, and while re sults can be reproduced, they may not apply 1-for-1 to your 2620 :-).

Hein.

[Andre Braganca]

English is not my native language, but I think I understood your ... french :-), and the rest !

After reading your answers and the linked documentation, it's clear for me what I should do. For the benefit of the forum, imho the first step would be to upgrade to 11v3 asap (late 2007 for this entry-level servers, I hear), because it's a totally rewritten OS and one should expect an overall performance improvement (20 to 30% the marketeers say). Then no theory, just give it a try. Measure the results and see if it is worth it. In doubt, switch it off !

Btw, looks as if Hyperthreading is enabled by default BUT the LCPUs aren't.

Regards and thanks you all
Andre'