percentages going over 100?

[orm011]

Hi there. First of all, thank you for the tools. I've learned a lot about how to use perf just by looking at how the pmu-tools do it.

I'm seeing this strange output in commit d70840b, using command line options ../pmu-tools/toplev.py --verbose --no-multiplex -l3 --single-thread -- ./myprogram

I consistently get this this printed output whose % is > 100 on a particular test program I am running.

BE Backend_Bound: 82.25 % [100.00%]
BE/Mem Backend_Bound.Memory_Bound: 57.41 % [100.00%]
BE/Mem Backend_Bound.Memory_Bound.L1_Bound: 5.58 % [100.00%]
This metric estimates how often the CPU was stalled without
loads missing the L1 data cache...
Sampling events: mem_load_retired.l1_hit:pp mem_load_retired.fb_hit:pp
BE/Mem Backend_Bound.Memory_Bound.L1_Bound.DTLB_Load: _ 196.05 %below _ [100.00%]
This metric represents cycles fraction where the TLB was
missed by load instructions...
Sampling events: mem_inst_retired.stlb_miss_loads:p

[orm011]

When not run with the --verbose flag, I see the following warning:
"warning: Mismeasured: DTLB_Load". It seems you have already checked for this sort of thing in the code (in function check_ratio), so maybe this is not an issue with pmu-tools but with the underlying counters? I can close in that case.

I'm curious, any guidance as to why this sort of thing would happen?

[andikleen]

A lot of the formulas only give meaningful results when their parent nodes crossed the threshold. You disabled that with -v. For more details on that see the Top Down paper (Yasin "A Top-Down method for ...")

[orm011]

I see. Thanks, I will look more closely into that.