cc-metric-collector/collectors/likwid/groups/phi/TLB_L1.txt

SHORT L1 TLB misses

EVENTSET
PMC0 DATA_PAGE_WALK
PMC1 DATA_READ_OR_WRITE

METRICS
Runtime (RDTSC) [s] time
L1 TLB misses [misses/s] PMC0/time
L1 TLB miss ratio PMC0/PMC1

LONG
Formulas:
L1 TLB misses [misses/s] = DATA_PAGE_WALK/time
L1 TLB miss ratio = DATA_PAGE_WALK/DATA_READ_OR_WRITE
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This performance group measures the L1 TLB misses. A L1 TLB miss that hits the
L2 TLB has a penelty of about 25 cycles for 4kB pages. For 2MB pages, the penelty
for a L1 TLB miss that hits L2 TLB is about 8 cycles. The minimal L1 TLB miss ratio
is about 1/64, so a high ratio indicates a bad spartial locality. Data of a page
is only partly accessed. It can also indicate trashing because when multiple pages
are accessed in a loop iteration, the size and associativity is not sufficient to
hold all pages.