Re: [RFC PATCH 0/8][Sorted-buddy] mm: Linux VM Infrastructure to support Memory Power Management

["Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>]

On 11/09/2012 09:43 PM, Dave Hansen wrote:
> On 11/09/2012 07:23 AM, Srivatsa S. Bhat wrote:
>> FWIW, kernbench is actually (and surprisingly) showing a slight performance
>> *improvement* with this patchset, over vanilla 3.7-rc3, as I mentioned in
>> my other email to Dave.
>>
>> https://lkml.org/lkml/2012/11/7/428
>>
>> I don't think I can dismiss it as an experimental error, because I am seeing
>> those results consistently.. I'm trying to find out what's behind that.
> 
> The only numbers in that link are in the date. :)  Let's see the
> numbers, please.
> 

Sure :) The reason I didn't post the numbers very eagerly was that I didn't
want it to look ridiculous if it later turned out to be really an error in the
experiment ;) But since I have seen it happening consistently I think I can
post the numbers here with some non-zero confidence.

> If you really have performance improvement to the memory allocator (or
> something else) here, then surely it can be pared out of your patches
> and merged quickly by itself.  Those kinds of optimizations are hard to
> come by!
> 

:-)

Anyway, here it goes:

Test setup:
----------
x86 2-socket quad-core machine. (CONFIG_NUMA=n because I figured that my
patchset might not handle NUMA properly). Mem region size = 512 MB.

Kernbench log for Vanilla 3.7-rc3
=================================

Kernel: 3.7.0-rc3-vanilla-default
Average Optimal load -j 32 Run (std deviation):
Elapsed Time 650.742 (2.49774)
User Time 8213.08 (17.6347)
System Time 1273.91 (6.00643)
Percent CPU 1457.4 (3.64692)
Context Switches 2250203 (3846.61)
Sleeps 1.8781e+06 (5310.33)

Kernbench log for this sorted-buddy patchset
============================================

Kernel: 3.7.0-rc3-sorted-buddy-default
Average Optimal load -j 32 Run (std deviation):
Elapsed Time 591.696 (0.660969)
User Time 7511.97 (1.08313)
System Time 1062.99 (1.1109)
Percent CPU 1448.6 (1.94936)
Context Switches 2.1496e+06 (3507.12)
Sleeps 1.84305e+06 (3092.67)

Regards,
Srivatsa S. Bhat