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From David Kerber <>
Subject Re: Performance for many small requests
Date Sat, 03 Sep 2011 17:23:01 GMT
On 9/3/2011 1:15 PM, Darius D. wrote:
> n828cl wrote:
>>> From: Darius D. []
>>> Subject: Re: Performance for many small requests
>>> in my opinion using 64bit JVM with such a small
>>> heap is only needed if performance testing shows
>>> gains versus 32bit JVM.
>> The main advantage of using a 64-bit JVM is the increased number of
>> registers available in the x86-64 architecture, which can result in vastly
>> reduced memory references.  Whether or not that's important to overall
>> performance is highly dependent on the application, of course.
> Yeah, but I'd err on 32bit JVM side :) Gains from more registers are very
> specific, but penalty from increased cache/TLB misses is big, and if you
> start hitting hard page faults ( that would have been avoidable due to lower
> heap size with 32bit JVM ) - even one of those will erase all gains :)

Then why shouldn't I just double my heap size?  Wouldn't that eliminate 
the risk of increased cache misses?  I was just using the settings from 
my 32-bit installation, but have plenty of RAM to allow me to increase 
the memory settings if that would help.


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