On Wed, Aug 31, 2016 at 12:05:14PM -0700, Vineet Gupta wrote: > On 08/26/2016 10:31 AM, Vineet Gupta wrote: > > On 08/25/2016 04:49 AM, Alexey Brodkin wrote: > >> ... > >> [PERF_COUNT_ARC_EDTLB] = "edtlb", /* D-TLB Miss */ > >> [PERF_COUNT_ARC_EITLB] = "eitlb", /* I-TLB Miss */ > >> + > >> + [PERF_COUNT_HW_CACHE_REFERENCES] = "imemrdc", /* Instr: mem read cached */ > >> + [PERF_COUNT_HW_CACHE_MISSES] = "dclm", /* D-cache Load Miss */ > > I think this is duplicating a mistake we already have. I vaguely remember when > > doing some hackbench profiling last year with range based profiling confined to > > memset routine and saw that L1-dcache-misses was counting zero. This is because it > > only counts LD misses while memset only does ST. > > > > Performance counter stats for '/sbin/hackbench': > > > > 0 L1-dcache-misses > > 0 L1-dcache-load-misses > > 1846082 L1-dcache-store-misses > > > > > > @PeterZ do you concur that is wrong and we ought to setup 2 counters to do this > > correctly ? > > Hi Peter / Will, > > Can you provide some guidance here. So I looked at what others do - > ARMV7_PERFCTR_L1_DCACHE_REFILL counts both load and store misses, while ARC has 2 > separate conditions for load or stores. Is there an existing mechanism to "group" > / "add" them to give a cumulative PERF_COUNT_HW_CACHE_MISSES Nope. So I would not try and use these generic events. In other news, it seems like there's finally some progress on the JSON patches: https://lkml.kernel.org/r/20160831114254.GA9001 at krava Which would make using non-standard events easier. > - is that what perf event grouping is ? Again, nope. Perf event groups are single counter (so no implicit addition) that are co-scheduled on the PMU. > Quoting from perf wiki @ https://perf.wiki.kernel.org/index.php/Tutorial > > "It can be interesting to try and pack events in a way that guarantees that event > A and B are always measured together. Although the perf_events kernel interface > provides support for event grouping, the current perf tool does *not*." That seems out-dated, Jiri added grouping support to perf-tool quite a while back. You can do it like: perf stat -e '{cycles,instructions}' Which will place the cycles event and the instructions event in a group and thereby guarantee they're co-scheduled.
