topic Re: Problem mon sys shows only CPU 0 in Operating System - OpenVMS

Problem mon sys shows only CPU 0

Alex Chupahin — Sat, 07 Jun 2008 03:34:37 GMT

Hello!
I experimented with threads, on my dual-processor rx1620 and find things, that
I cannot understand - threaded program that
much faster under Unix is slower under VMS.
I just look
$ mon sys

and see only CPU 0!

while
EFI shows me 2 CPU configured withput errors and installed,
$show cpu
shows me
two CPU.
System: A, HP rx1620 (1.60GHz/3.0MB)

CPU ownership sets:
Active 0,1
Configure 0,1

CPU state sets:
Potential 0,1
Autostart 0,1
Powered Down None
Not Present None
Hard Excluded None
Failover None

Any ideas?

Re: Problem mon sys shows only CPU 0

Hein van den Heuvel — Sat, 07 Jun 2008 04:03:48 GMT

>> $ mon sys
>> and see only CPU 0!

Alex,

forgive me if this is too stupid, but how do you 'see' CPU 0 with 'mon sys'.

The output looks like:
CPU 0 +--------- ... --------+ 200

That 0 is a 0 - base, not 'which' CPU.
The 200 is 200% suggesting 2 CPUs active.

The only Monitor screen which identified individual CPUs is MONI MODE/CPU.
Not terribly convenient.

The best display is T4 really.... IMHO

Cheers,
Hein.

Re: Problem mon sys shows only CPU 0

Hoff — Sat, 07 Jun 2008 04:14:11 GMT

OpenVMS I64 version and ECO level?

MONITOR should show a range of 0 to 200% here. One bar, but longer, and shown in aggregate across all processors.

MONITOR is a system-wide performance tool, and generally ill-suited for per-application monitoring.

As for determining application performance, DECset Performance and Coverage Analyzer (PCA) is a choice, or otherwise, and use these tools to profile the code. Or embed your own performance-monitoring calls (and any debugging needed). There are some fairly simple tools around in base OpenVMS that can monitor program counter addresses; these are within ANALYZE /SYSTEM most usually.

One of the usual triggers for performance differences between Unix and OpenVMS applications involves differences in file I/O. Unix file I/O is different than OpenVMS; it tends to stay in memory, where OpenVMS I/O tends to write the data to disk. OpenVMS also has issues when file extent sizes are at their default values and when volumes of data are being written.

But I'm not going to particularly speculate further. Use DECset PCA or another tool, and find out where the code is spending its time.

Do use caution here with some of the Itanium processors -- including the 1.6 GHz series processors you have here -- as you can see the hyperthreads show up as processors, too. (IIRC, this hyperthreading isn't turned on by default.)

Re: Problem mon sys shows only CPU 0

Alex Chupahin — Sat, 07 Jun 2008 09:13:27 GMT

Thank you very much,
Ð Ðº, I remeber I really saw 200% (it seems)
So it should be two processors.

Hmm, trouble still here.

I have a program that can work with and without POSIX threads. (I will say tomorrow what program is - it is at home)
that much faster on 2 CPUs with threads mode under UNIX (Linux also) than without threads.

On OpenVMS this program in threaded mode runs slower then without.

Re: Problem mon sys shows only CPU 0

Hoff — Sat, 07 Jun 2008 20:03:15 GMT

{{{{I have a program that can work with and without POSIX threads. (I will say tomorrow what program is - it is at home)
that much faster on 2 CPUs with threads mode under UNIX (Linux also) than without threads.

On OpenVMS this program in threaded mode runs slower then without.}}}}

This looks to be a "how high is up?" sort of question. AFAIK, there can be no answer to this one.

The performance aspects and the general implementations of Unix and of OpenVMS are different. Very different. Different I/O. Different threading. Different synchronization. Different scheduling. Just plain different.

OpenVMS I64 on Intel Itanium adds another layer to this whole discussion, with its comparatively massive performance penalty for unaligned references. (If this C code is generating gazillions of unaligned data references, performance will plummet.)

It is also easily feasible here that the Unix or Linux boxes here are simply faster than this rx1620 box. Check the SPEC numbers for both int and for rate, for instance.

Profile the application code. DECset PCA, et al.

Also look for alignment faults. Using the ANALYZE /SYSTEM (SDA) tool FLT or otherwise.

Re: Problem mon sys shows only CPU 0

Alex Chupahin — Thu, 12 Jun 2008 09:28:55 GMT

Still having troubles with.
It seems I have no appropriate licenses
I'm using hobbyst.
What licenses should I have to work with dual-processor system?

Re: Problem mon sys shows only CPU 0

Ian Miller. — Thu, 12 Jun 2008 10:24:45 GMT

How many units does your OPENVMS-I64-* licence have?

Re: Problem mon sys shows only CPU 0

Hoff — Thu, 12 Jun 2008 12:36:44 GMT

The hobbyist program traditionally requires two sets of PAKs, the base PAK for the platform (which is the FOE Foundation Operating Environment PAK on OpenVMS I64) and requires a second and separate set of PAKs for the layered products.

Some reading material:

http://64.223.189.234/node/31
http://64.223.189.234/node/259

Re: Problem mon sys shows only CPU 0

Alex Chupahin — Thu, 12 Jun 2008 13:09:10 GMT

This is my hobby licenses on the Itanium (I've got it from montagar)

OPENVMS-ALPHA-USER HP 0 1 100 0.0 (none) 20-NOV-2008
OPENVMS-HOBBYIST HP 0 1 100 0.0 (none) 20-NOV-2008
OPENVMS-I64-FOE HP 100 1 0 0.0 (none) 20-NOV-2008