Virtual processors

Question

Hi,
Was wondering if someone would be able to shed some light on a few questions I have regarding virtual processors on a T5220 server?
1.) I have a perl program (not threaded) that runs a certain amount of time on a Intel based HP server with a 2.2 Mhz processor. The same script runs about 4 times slower on a T5220, 8 Core, 64GB RAM server.
Now I see that there are 64 1.2 Mhz virtual processors on this server and since the perl script is not multi-threaded, I assume it uses just one of the virtual processors? And running at 1.2 Mhz, it is much slower than my old Intel box, is that right?
2.) Now the question is, can these virtual processors be reconfigured to less, but more powerful processors or am I missing the boat here?
3.) If I am missing the boat, are there any suggestions on how I can speed up my perl script on this powerful machine?
Regards,
Boela.
Edited by: Boela on Aug 27, 2009 4:46 AM

Answer 1

Hi Kosie
As you have seen, the coolthreads servers are very good at running multi-threaded processes or many single threaded processes, but poor when it comes to running one single threaded processes quickly. These machines work best on large multithreaded workloads, such as high volume webserving.
In your case it sounds like your server has 8 cores and each core can run 8 concurrent threads, this gives you a total of 64VCPUs.
In answer to your questions.
1) If your perl program is single threaded then yes it will only use one of the 64 Virtual CPUS. If you look at prstat or similar, the most CPU that process will use on the server is 100/64 = approx 1.6%. To use the rest of the processing power available on the T5220 your script will need to become multithreaded. And depending on what it does, that may not be easy. So you may have to just accept that there is no easy way to make it run faster on the T5220 as it stands. When it comes to single threaded performance the T5220s are typically slower than a modern x86 machine.
2) No you cant configure the VCPUS to be fewer in number and greater in processor speed.
3) To make your script run faster you will need to either tune it or if possible make it multithreaded, or split the workload up into chunks and run multiple instances of the perl script.
Sorry, but no easy solution to your problem.