[Barrelfish-users] Running benchmark on multiple cores

Georgios Varisteas yorgos at kth.se
Tue Oct 4 17:04:58 CEST 2011


Qemu emulates up to 255 cores. However, it actually uses a single physical core only. In other words it is not a parallel application.

So although Barrelfish thinks it has multiple cores available, it runs sequentially. You can use qemu for testing and debugging but not for measurements.

Other emulators like virtualbox and vmware actually map virtual cores to physical cores. Thus they are better fitted for benchmarks like bomp. Their tradeoff is that they can have as many virtual cores as there are physical ones only.

best regards,
Georgios Varisteas

Sent from my Android phone with K-9 Mail. Please excuse my brevity.

lijl at umich.edu wrote:

Hi Georgios,

Thank you for your reply. So you mean, by using Qemu, even barrelfish
claims that it is running on multiple cores, it is actually running only on
1 core?



On Tue, 4 Oct 2011 07:24:59 +0000, Georgios Varisteas <yorgos at kth.se>
> Hi
> I assume you are using Qemu. The downside with this emulator is that it
> will only use one core from the underlying system, even though you can
> it to emulate up to 255. Also, you can not use the host OS' monitoring
> tools to check on any emulator's load, as they will constantly appear as
> using 100% of the core(s) they run on.
> I have tested BOMP myself and it runs correctly. I propose to use a
> different emulator. I have found VirtualBox to be a very good tool for
> quick and easy trials.
> Best regards,
> Georgios Varisteas

> From: Baumann Andrew [andrewb at inf.ethz.ch]
> Sent: Tuesday, October 04, 2011 05:26
> To: lijl at umich.edu; barrelfish-users at lists.inf.ethz.ch
> Subject: Re: [Barrelfish-users] Running benchmark on multiple cores
> Hi,
> Can you paste the menu.lst file or fish command you used to run the
> benchmark? Did you pass the number of threads to use as the command-line
> argument to the benchmark programs?
> What do you mean by "when I check the system monitor"?
> Andrew
>> -----Original Message-----
>> From: lijl at umich.edu [mailto:lijl at umich.edu]
>> Sent: Monday, 3 October 2011 19:27
>> To: barrelfish-users at lists.inf.ethz.ch
>> Subject: [Barrelfish-users] Running benchmark on multiple cores
>> Hi,
>> I was trying to run the bomp benchmarks (with multiple threads) on
>> barrelfish. However, no matter how many cores I turned on (or off), the
>> result is always similar to that of a single core. It seems that only 1
>> core is busy doing the job when I check the system monitor. I appreciate
>> if
>> anyone could tell me how to run these benchmarks simultaneously on
>> multiple
>> cores.
>> Thanks,
>> Jialin Li
>> University of Michigan
>> Computer Engineering
>> Advanced Computer Architecture Lab

>> Barrelfish-users mailing list
>> Barrelfish-users at lists.inf.ethz.ch
>> https://lists.inf.ethz.ch/mailman/listinfo/barrelfish-users

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> Barrelfish-users at lists.inf.ethz.ch
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