Re: Tuning suggestions, please?

Nigel Wade <>
Wed, 04 Jul 2007 15:47:37 +0100
Bret Schuhmacher wrote:

Thanks for the code, Nigel. Here's the output:
15 193573
16 186582
16 190201
15 183223
16 116424
16 123012
15 100954
16 183436
15 170407
16 180246
16 195359
15 186473
16 190119
16 148391

Looks like the timer resolution on my laptop running Windows XP is 15-16ms -
consistent with the 15-16 ms I was trying to track down.

I originally saw the issue at a customer's site on an AIX v5.2 box and
replicated it on my Windows laptop. Is it possible an AIX box has the same
timer resolution a Windows box does? I see the same issues inside and
outside of Eclipse, as well as under different JVM versions (for those of
you who were asking).

Is there *anything* I can do about this? Sounds like it's hardwired into
the CPU. I tried adding this:
              Thread thisThread = Thread.currentThread();
But it didn't help.

Are there other ways of dedicating a CPU or increasing the timeslice or
priority to a thread in Java? Would it help?

Thanks again, Nigel!



You don't need to do anything. Your CPU is getting 100% (or pretty much). The
only issue is the time resolution - you can't resolve the time to better than

In the above test output you can see that during the 15ms resolution of your
clock the code is actually running round the loop between 100,000 and 200,000

Nigel Wade, System Administrator, Space Plasma Physics Group,
            University of Leicester, Leicester, LE1 7RH, UK
E-mail :
Phone : +44 (0)116 2523548, Fax : +44 (0)116 2523555

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