TLB impact on VM performance

[Xin Tong]

On Wed, Nov 28, 2012 at 5:13 AM, Aleksey Shipilev
<aleksey.shipilev at oracle.com> wrote:
> On 11/28/2012 10:14 AM, Xin Tong wrote:
>> I recently took some data on the performance of hotspot when hugepage
>> is enabled/disabled. i found a performance difference of ~20% on
>> specjbb with -Xms1024m -Xmx2048m running 4 whs. the nursery heap size
>> is ~600M and tenure is ~500M.
>>
>> OS: Linux socrates 3.2.0-33-generic #52-Ubuntu SMP Thu Oct 18 16:29:15
>> UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
>> CPU: model name      : Intel(R) Core(TM) i5-2410M CPU @ 2.30GHz
>>
>> I am wondering does hugepage demostrate performance improvements on
>> other benchmarks as well ? i see a much smaller difference for dacapo
>> benchmarks.
>
> My interpretation: SPECjbb is known to be very memory-access intensive,
> that is why improving TLB accesses gives you huge payoffs. Many Dacapo
> benchmarks are compute-bound, and the TLB performance while important is
> not having the same impacts.
>
> Many characteristic Java applications are as promiscuous with memory as
> SPECjbb, and so large pages demonstrate significant improvements on
> business workloads we have internally.
>

What other publicly available workloads would demonstrate similar
performance benefit with hugepage other than SPECJbb2005 would you
think ? maybe JGrande ?

Xin

> -Aleksey.