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From "Darius D." <darius....@gmail.com>
Subject RE: Performance for many small requests
Date Sat, 03 Sep 2011 22:11:53 GMT



Jeff Sturm wrote:
> 
> 
> The Linux JVM has a nice option -XX:+UseLargePages to help avoid TLB
> misses on heap accesses.  It's good for modest gains, and has the side
> effect of locking the heap into memory.  I tend to use it on systems with
> large heaps.
> 
> Not much you can do about cache misses though, besides getting processors
> with more cache.
> 
> 


Yeah, Large(Huge) pages is big, free 10-15% perf if app is memory heavy. And
as a bonus you also reduce the size of kernel page translation tables (
works wonders if you are using for example Oracle that is using shared mem
for "instances", savings can be up to gigabytes on big systems ).

Even greater news is that recent Linux kernel versions ( i think 2.6.38 and
above ) have so called Transparent Huge Pages - that basically enable them
with some magic for all processes, giving 95% of HugePages benefits without
LargePages penalties (heap locking/pinning  and app specific config). So
users of virtualisation, databases and JVMs with large heaps can rejoice :)
-- 
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