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Re: [PATCH] Enabling Software Prefetching by Default at -O3
On Tue, Jun 15, 2010 at 3:55 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Tue, Jun 15, 2010 at 3:47 PM, Mark Mitchell <mark@codesourcery.com> wrote:
>> Fang, Changpeng wrote:
>>
>>>> Is that rate or speed? I would like to see numbers on Intel Core i7 if you are
>>>> proposing enable it by default for x86.
>>
>> HJ, are you in position to test this on Core i7? ?Since you work at
>> Intel, it seems like it might be easier for you to do it than for the
>> folks at AMD to do it?
>
> We never tried software prefetch since Intel processors rarely need
> it. ?We will try it. It will take some times.
>
Here are what we got on Intel Core i7 64bit with -O3 vs -O3
-fprefetch-loop-arrays:
400.perlbench -0.369004%
401.bzip2 -3%
403.gcc -1.5748%
429.mcf 0.784314%
445.gobmk -1.28755%
456.hmmer -1.67364%
458.sjeng 0%
462.libquantum 2.57827%
464.h264ref -0.806452%
471.omnetpp -1.51515%
473.astar -0.581395%
483.xalancbmk 0%
SPECint(R)_base2006 -0.766284%
410.bwaves -1.27796%
416.gamess -1.2605%
433.milc 0%
434.zeusmp 1.24481%
435.gromacs -0.478469%
436.cactusADM -5.07813%
437.leslie3d -1.10294%
444.namd 0%
450.soplex 0.628931%
453.povray 0.392157%
454.calculix 0%
459.GemsFDTD -1.51515%
465.tonto 0%
470.lbm -1.16279%
481.wrf -0.442478%
482.sphinx3 2.51397%
SPECfp(R)_base2006 -0.769231%
It doesn't help Intel Core i7. I think it should be enabled
with -mtune=XXX on x86 where prefetch improves
performance on XXX.
--
H.J.