Hi,
I ran microarchitecture analysis on 8280 processor and i am looking for usage metrics related to cache utilization like - L1,L2 and L3 Hit/Miss rate (total L1 miss/total L1 requests ...., total L3 misses / total L3 requests) for the overall application. I was unable to see these in the vtune GUI summary page and from this article it seems i may have to figure it out by using a "custom profile".
From the explanation here (for sandybridge) , seems we have following for calculating "cache hit/miss rates" for demand requests-
Demand Data L1 Miss Rate => cannot calculate.
Demand Data L2 Miss Rate =>
(sum of all types of L2 demand data misses) / (sum of L2 demanded data requests) =>
(MEM_LOAD_UOPS_RETIRED.LLC_HIT_PS + MEM_LOAD_UOPS_LLC_HIT_RETIRED.XSNP_HIT_PS + MEM_LOAD_UOPS_LLC_HIT_RETIRED.XSNP_HITM_PS + MEM_LOAD_UOPS_MISC_RETIRED.LLC_MISS_PS) / (L2_RQSTS.ALL_DEMAND_DATA_RD)Demand Data L3 Miss Rate =>
L3 demand data misses / (sum of all types of demand data L3 requests) =>
MEM_LOAD_UOPS_MISC_RETIRED.LLC_MISS_PS / (MEM_LOAD_UOPS_RETIRED.LLC_HIT_PS + MEM_LOAD_UOPS_LLC_HIT_RETIRED.XSNP_HIT_PS + MEM_LOAD_UOPS_LLC_HIT_RETIRED.XSNP_HITM_PS + MEM_LOAD_UOPS_MISC_RETIRED.LLC_MISS_PS)
Q1: As this post was for sandy bridge and i am using cascadelake, so wanted to ask if there is any change in the formula (mentioned above) for calculating the same for latest platform and are there some events which have changed/added in the latest platform which could help to calculate the -
- L1 Demand Data Hit/Miss rate
- L1,L2,L3 prefetch and instruction Hit/ Miss rate
also, in this post here , the events mentioned to get the cache hit rates does not include ones mentioned above (example MEM_LOAD_UOPS_RETIRED.LLC_HIT_PS)
amplxe-cl -collect-with runsa -knob event-config=CPU_CLK_UNHALTED.REF_TSC,MEM_LOAD_UOPS_RETIRED.L1_HIT_PS,MEM_LOAD_UOPS_RETIRED.L1_MISS_PS,MEM_LOAD_UOPS_RETIRED.L3_HIT_PS,MEM_LOAD_UOPS_RETIRED.L3_MISS_PS,MEM_UOPS_RETIRED.ALL_LOADS_PS,MEM_UOPS_RETIRED.ALL_STORES_PS,MEM_LOAD_UOPS_RETIRED.L2_HIT_PS:sa=100003,MEM_LOAD_UOPS_RETIRED.L2_MISS_PS -knob collectMemBandwidth=true -knob dram-bandwidth-limits=true -knob collectMemObjects=true
Q2: what will be the formula to calculate cache hit/miss rates with aforementioned events ?
Q3: is it possible to get few of these metrics (like MEM_LOAD_UOPS_MISC_RETIRED.LLC_MISS_PS,... ) from the uarch analysis 's raw data which i already ran via -
mpirun -np 56 -ppn 56 amplxe-cl -collect uarch-exploration -data-limit 0 -result-dir result_uarchexpl -- $PWD/app.exe
So, the following will the correct way to run the custom analysis via command line ? -
mpirun -np 56 -ppn 56 amplxe-cl -collect-with runsa -data-limit 0 -result-dir result_cacheexpl -knob event-config=MEM_LOAD_UOPS_RETIRED.LLC_HIT_PS,MEM_LOAD_UOPS_LLC_HIT_RETIRED.XSNP_HIT_PS,MEM_LOAD_UOPS_LLC_HIT_RETIRED.XSNP_HITM_PS,L2_RQSTS.ALL_DEMAND_DATA_RD,MEM_LOAD_UOPS_MISC_RETIRED.LLC_MISS_PS,CPU_CLK_UNHALTED.REF_TSC,MEM_LOAD_UOPS_RETIRED.L1_HIT_PS,MEM_LOAD_UOPS_RETIRED.L1_MISS_PS,MEM_LOAD_UOPS_RETIRED.L3_HIT_PS,MEM_LOAD_UOPS_RETIRED.L3_MISS_PS,MEM_UOPS_RETIRED.ALL_LOADS_PS,MEM_UOPS_RETIRED.ALL_STORES_PS,MEM_LOAD_UOPS_RETIRED.L2_HIT_PS:sa=100003,MEM_LOAD_UOPS_RETIRED.L2_MISS_PS -- $PWD/app.exe
(please let me know if i need to use more/different events for cache hit calculations)
Q4: I noted that to calculate the cache miss rates, i need to get/view data as "Hardware Event Counts", not as "Hardware Event Sample Counts".https://software.intel.com/en-us/forums/vtune/topic/280087 How do i ensure this via vtune command line? as I generate summary via -
vtune -report summary -report-knob show-issues=false -r <my_result_dir>.
Let me know if i need to use a different command line to generate results/event values for the custom analysis type.