cc-metric-collector/collectors/likwid/groups/knl/L2CACHE.txt
2021-03-25 14:47:10 +01:00

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SHORT L2 cache miss rate/ratio
EVENTSET
FIXC0 INSTR_RETIRED_ANY
FIXC1 CPU_CLK_UNHALTED_CORE
FIXC2 CPU_CLK_UNHALTED_REF
PMC0 MEM_UOPS_RETIRED_L2_HIT_LOADS
PMC1 MEM_UOPS_RETIRED_L2_MISS_LOADS
METRICS
Runtime (RDTSC) [s] time
Runtime unhalted [s] FIXC1*inverseClock
Clock [MHz] 1.E-06*(FIXC1/FIXC2)/inverseClock
CPI FIXC1/FIXC0
L2 request rate (PMC0+PMC1)/FIXC0
L2 miss rate PMC1/FIXC0
L2 miss ratio PMC1/(PMC0+PMC1)
LONG
Formulas:
L2 request rate = (MEM_UOPS_RETIRED_L2_HIT_LOADS+MEM_UOPS_RETIRED_L2_MISS_LOADS)/INSTR_RETIRED_ANY
L2 miss rate = MEM_UOPS_RETIRED_L2_MISS_LOADS/INSTR_RETIRED_ANY
L2 miss ratio = MEM_UOPS_RETIRED_L2_MISS_LOADS/(MEM_UOPS_RETIRED_L2_HIT_LOADS+MEM_UOPS_RETIRED_L2_MISS_LOADS)
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This group measures the locality of your data accesses with regard to the
L2 cache. L2 request rate tells you how data intensive your code is
or how many data accesses you have on average per instruction.
The L2 miss rate gives a measure how often it was necessary to get
cache lines from memory. And finally L2 miss ratio tells you how many of your
memory references required a cache line to be loaded from a higher level.
While the data cache miss rate might be given by your algorithm you should
try to get data cache miss ratio as low as possible by increasing your cache
reuse.