(trimmed Cc list a little) On Mon, 5 Oct 2015 14:20:45 -0700 Andi Kleen <ak@xxxxxxxxxxxxxxx> wrote: > > My only problem left, is I want a perf measurement that pinpoint these > > kind of spots. The difference in L1-icache-load-misses were significant > > (1,278,276 vs 2,719,158). I tried to somehow perf record this with > > different perf events without being able to pinpoint the location (even > > though I know the spot now). Even tried Andi's ocperf.py... maybe he > > will know what event I should try? > > Run pmu-tools toplev.py -l3 with --show-sample. It tells you what the > bottle neck is and what to sample for if there is a suitable event and > even prints the command line. > > https://github.com/andikleen/pmu-tools/wiki/toplev-manual#sampling-with-toplev > My result from (IP-forward flow hitting CPU 0): $ sudo ./toplev.py -I 1000 -l3 -a --show-sample --core C0 So, what does this tell me?: C0 BAD Bad_Speculation: 0.00 % [ 5.50%] C0 BE Backend_Bound: 100.00 % [ 5.50%] C0 BE/Mem Backend_Bound.Memory_Bound: 53.06 % [ 5.50%] C0 BE/Core Backend_Bound.Core_Bound: 46.94 % [ 5.50%] C0-T0 FE Frontend_Bound.Frontend_Latency.Branch_Resteers: 5.42 % [ 5.50%] C0-T0 BE/Mem Backend_Bound.Memory_Bound.L1_Bound: 54.51 % [ 5.50%] C0-T0 BE/Core Backend_Bound.Core_Bound.Ports_Utilization: 20.99 % [ 5.60%] C0-T0 CPU utilization: 1.00 CPUs [100.00%] C0-T1 FE Frontend_Bound.Frontend_Latency.Branch_Resteers: 6.04 % [ 5.50%] C0-T1 CPU utilization: 1.00 CPUs [100.00%] Unfortunately the perf command it gives me fails with: "invalid or unsupported event". Perf command: perf record -g -e cpu/event=0xc5,umask=0x0,name=Branch_Resteers_BR_MISP_RETIRED_ALL_BRANCHES:pp,period=400009/pp,cpu/event=0xd,umask=0x3,cmask=1,name=Bad_Speculation_INT_MISC_RECOVERY_CYCLES,period=2000003/,cpu/event=0xd1,umask=0x1,name=L1_Bound_MEM_LOAD_UOPS_RETIRED_L1_HIT:pp,period=2000003/pp,cpu/event=0xd1,umask=0x40,name=L1_Bound_MEM_LOAD_UOPS_RETIRED_HIT_LFB:pp,period=100003/pp -C 0,4 -a > However frontend issues are difficult to sample, as they happen very far > away from instruction retirement where the sampling happens. So you may > have large skid and the sampling points may be far away. Skylake has new > special FRONTEND_* PEBS events for this, but before it was often difficult. This testlab CPU is i7-4790K @ 4.00GHz. Maybe I should get a Skylake... p.s. thanks for your pmu-tools[1], even-though I don't know how to use most of them ;-) -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat Author of http://www.iptv-analyzer.org LinkedIn: http://www.linkedin.com/in/brouer [1] https://github.com/andikleen/pmu-tools -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>