Is it a single lgroup? 1GB pages might mean remote memory for one of the
CPUs, and local for another.
Is it really TLB misses - does cputrack show an increase in TLB misses?
Do you get more cache misses?
Does pmap indicate that the app got large pages?
Regards,
Darryl.
On 8/20/2010 9:43 PM, Kishore Kumar Pusukuri wrote:
Hi,
My AMD Opteron supports 4KB, 2MB and 1GB page sizes. I observed that there is
performance improvement (reduced elapsed time) for some multi-threaded
applications when I used 2MB page-size for heap. These applications need around
650MB heap (it reads a huge file of around 650MB size). However, when I used
1GB pages for heap, there is performance degradation for these programs. If we
use 1 GB, then one page is enough to satisfy the heap space, right? Then, why
we see performance degradation in this case. Please let me know.
$ pagesize -a
4096
2097152
1073741824
--
Darryl Gove
Compiler Performance Engineering
Blog : http://blogs.sun.com/d/
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http://my.safaribooksonline.com/9780768681390
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