[concurrency-interest] Some interesting (confusing?) benchmark results

Vitaly Davidovich vitalyd at gmail.com
Wed Feb 13 08:47:00 EST 2013


If you're using an affinity mask, sure.  The advantage of having this in
jdk is cross platform support and not having people write the same code
across their apps.

Sent from my phone
On Feb 13, 2013 8:39 AM, "Stanimir Simeonoff" <stanimir at riflexo.com> wrote:

>
>
> On Wed, Feb 13, 2013 at 3:32 PM, Vitaly Davidovich <vitalyd at gmail.com>wrote:
>
>> /proc/cpuinfo parsing is the way to go but would be nice to have a
>> "machine spec/capability" API baked into the JDK.
>>
>> But you still to get info on which CPU the process is limited to, i.e.
> affinity. Which is the harder task. OTOH, /proc/cpuinfo is quite trivial to
> parse.
>
> Stanimir
>
>> Sent from my phone
>> On Feb 13, 2013 5:49 AM, "Stanimir Simeonoff" <stanimir at riflexo.com>
>> wrote:
>>
>>>
>>> Is there a way to know how many physical processors are available on the
>>>> JVM?
>>>>
>>>> On linux you can use taskset -p <pid>
>>> (pid you can retrieve form /proc/self )
>>> and you can use /proc/cpuinfo to determine which processors have
>>> siblings.
>>>
>>> Quite inconvenient overall. So kernels might have /proc/self/affinity
>>> which would make life easier .
>>> And of course there is JNI and syscall.
>>>
>>> Stanimir
>>>
>>>
>>>
>>>> Cheers,
>>>>>>>>
>>>>
>>>>>
>>>>>
>>>>> Nathan Reynolds<http://psr.us.oracle.com/wiki/index.php/User:Nathan_Reynolds>| Architect |
>>>>> 602.333.9091
>>>>> Oracle PSR Engineering <http://psr.us.oracle.com/> | Server Technology
>>>>>  On 2/12/2013 2:18 PM, √iktor Ҡlang wrote:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Tue, Feb 12, 2013 at 8:28 PM, Kirk Pepperdine <kirk at kodewerk.com>wrote:
>>>>>
>>>>>> >
>>>>>> > Do you agree that thread pool sizing depends on type of work? (IO
>>>>>> bound vs CPU bound, bursty vs steady etc etc)
>>>>>>  Yes
>>>>>> > Do you agree that a JVM Thread is not a unit of parallelism?
>>>>>>  Yes
>>>>>> > Do you agree that having more JVM Threads than hardware threads is
>>>>>> bad for CPU-bound workloads?
>>>>>>  No, even with CPU bound workloads I have found that the hardware/OS
>>>>>> is much better at managing many workloads across many threads than I am. So
>>>>>> a few more threads is ok, many more threads is bad fast.
>>>>>>
>>>>>
>>>>>  That's an interesting observation. Have any more data on that?
>>>>> (really interested)
>>>>> As I said earlier, for CPU-bound workloads we've seen the best
>>>>> performance when only loading 60-70% of the cores (other threads exist on
>>>>> the machine of course).
>>>>>
>>>>>  Cheers,
>>>>>
>>>>>>>>>>
>>>>>
>>>>>>
>>>>>> Regards,
>>>>>> Kirk
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>  --
>>>>> *Viktor Klang*
>>>>> *Director of Engineering*
>>>>> *
>>>>> *
>>>>> Typesafe <http://www.typesafe.com/> - The software stack for
>>>>> applications that scale
>>>>> Twitter: @viktorklang
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Concurrency-interest mailing listConcurrency-interest at cs.oswego.eduhttp://cs.oswego.edu/mailman/listinfo/concurrency-interest
>>>>>
>>>>>
>>>>>
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>>>>>
>>>>
>>>>
>>>> --
>>>> *Viktor Klang*
>>>> *Director of Engineering*
>>>> *
>>>> *
>>>> Typesafe <http://www.typesafe.com/> - The software stack for
>>>> applications that scale
>>>> Twitter: @viktorklang
>>>>
>>>> _______________________________________________
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>
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