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SubjectRe: perf tools miscellaneous questions
Date
Francis Moreau <francis.moro@gmail.com> writes:

> Francis Moreau <francis.moro@gmail.com> writes:
>

[...]

>>
>> How could I know the number of cache level on my cpu ?
>>
>> I tried:
>>
>> $ perf stat -e cache-misses:u,l1d-loads-misses:u true
>>
>> Performance counter stats for 'true':
>>
>> 802 cache-misses
>> 937 L1-dcache-load-misses
>>
>> 0.000996578 seconds time elapsed
>>
>> $ perf stat -e cache-misses:u,L2-loads-misses:u true
>>
>> Performance counter stats for 'true':
>>
>> 788 cache-misses
>> 95 LLC-load-misses
>>
>> 0.001025423 seconds time elapsed
>>
>> So it looks like you're right: in my case I have this cache
>> configuration:
>>
>
> oops sorry, I replied too early...
>
> so my cache configuration is:
>
> L1 -> L2 -> LLC
>
> where L2 misses is given by: 'cache-misses' - 'LLC-load-misses'
>
> Is that correct ?
>
> If so, I found 'cache-misses' term very not intuitive IMHO, probably
> because I'm not an expert in cpu caches...

Well thinking more about it, the above is wrong and I'm lost.

If 'cache-misses' is the last level cache misses then how to interpret
these results ?

$ perf stat -e llc-load-misses:u,llc-store-misses:u true

Performance counter stats for 'true':

94 LLC-load-misses
0 LLC-store-misses

0.000981840 seconds time elapsed


$ perf stat -e cache-misses:u true

Performance counter stats for 'true':

796 cache-misses

0.001345136 seconds time elapsed

Here 'cache-misses' value is much more than llc misses one...

--
Francis


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