cache misses measure

cache misses measure

Hi,

I would like to measure L1 & L2 cache miss & cache miss rate on a Pentium III processor.

Should the counters to be used are L1_Lines_Allocated, L2_Lines_Allocated and Data_Memory_References (i.e., does L1 cache miss rate = L1_Lines_Allocated/ Data_Memory_References)?

Thanks,

Harel

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Hey Harel,

Did you chec out the reference manual, which is a fairly nice encyclopedia of processor events? I'm guessing you DID, but just in case, here's how you'd find it (paths are defaults):

$ cd /opt/intel/vtune/doc
$ cd reference
$ mozilla index.htm # or just load the index.htm file into your favorite browser

cheers
jdg

I did check the refernce manual, and "chose" the above counters according to these descriptions. I posted the question since i did not find any explicit indication of what is considered the overall cache miss counter, and how the cache miss rate can be calculated.

Thanks,
Harel

OK that's what I thought. Thanks for the confirm. I'll check around here and report back.

cheers
jdg

That's right approach.
Except that you may use VTune's ratios:
L1 read misses ratio, L1 write misses ratio - together they give you a percentage of L1 misses
L2 misses per data memory reference - percentage of all L2 misses relative to all memory references.

Thanks for the tip.

How do I ger these VTune's ratios (L1 read misses ratio, L1 write misses ratio, L2 misses per data memory reference). I am using Pentium III, and I do not find these counters.Are these couters available on Pentium III?

Thanks,
Harel

Go to sampling->configure->event ratios, choose smth like memory statistics group or all and search there for these ratios. They are P3 specific

> Go to sampling->configure->event ratios, choose smth like memory statistics group > or all and search there for these ratios.

I don't see any "event ratios" option.
When going through sampling->configure->event, i get to a screen which present "Events groups" option, and "Available events option". Then, I select from"Available events option"the "selected events".
Idon't see any ratio event althoughlooking in the "All events" option. It also seems that when modifying the events group, the availbale events remain the same.

Thanks,
Harel

Are we all on the same page, guys?

Running vtlec, VTune 3.0 for Linux?

jdg

Yes- I am running vtlec, VTune 3.0 for Linux...

I am sorry, this works for Windows only. I did not pay attention that this is Linux analyser discussion...

Event ratios are not yet supported on Linux. To do this somewhat manually, configure sampling of the events based on fixed sample-after-values (SAV)with nice even numbers (powers of 10 are easiest - pick an SAV close to what was already determined by VTune), and turn off calibration. This will allow easy ratios to be determined just by inspection.

cpolson wrote:

Event ratios are not yet supported on Linux. To do this somewhat manually, configure sampling of the events based on fixed sample-after-values (SAV) with nice even numbers (powers of 10 are easiest - pick an SAV close to what was already determined by VTune), and turn off calibration. This will allow easy ratios to be determined just by inspection.

Hi,
Is this supported now!!! i mean GUI analysis of event ratios..?

thanks in advance
Bijilash

cpolson was indicating that version 3.0 does not support ratios in the GUI. 3.0 is the current release and there is no release scheduled for the near future. You must still do the ratio calculations in your head or on paper.

Regards,
MrAnderson

DaveA,

What is this mysterious stuff "paper" of which you speak???????

:))))

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