Messages in this thread Patch in this message | | | Date | Sat, 26 Mar 2022 14:23:03 +0800 | From | Leo Yan <> | Subject | Re: [PATCH v4 4/4] perf mem: Support HITM for when mem_lvl_num is any |
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On Thu, Mar 24, 2022 at 06:33:23PM +0000, Ali Saidi wrote: > For loads that hit in a the LLC snoop filter and are fulfilled from a > higher level cache on arm64 Neoverse cores, it's not usually clear what > the true level of the cache the data came from (i.e. a transfer from a > core could come from it's L1 or L2). Instead of making an assumption of > where the line came from, add support for incrementing HITM if the > source is CACHE_ANY. > > Since other architectures don't seem to populate the mem_lvl_num field > here there shouldn't be a change in functionality. > > Signed-off-by: Ali Saidi <alisaidi@amazon.com> > Tested-by: German Gomez <german.gomez@arm.com> > Reviewed-by: German Gomez <german.gomez@arm.com> > --- > tools/perf/util/mem-events.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/tools/perf/util/mem-events.c b/tools/perf/util/mem-events.c > index e5e405185498..084977cfebef 100644 > --- a/tools/perf/util/mem-events.c > +++ b/tools/perf/util/mem-events.c > @@ -539,6 +539,15 @@ do { \ > stats->ld_llchit++; > } > > + /* > + * A hit in another cores cache must mean a llc snoop > + * filter hit > + */ > + if (lnum == P(LVLNUM, ANY_CACHE)) { > + if (snoop & P(SNOOP, HITM)) > + HITM_INC(lcl_hitm); > + }
This might break the memory profiling result for x86, see file arch/x86/events/intel/ds.c:
97 void __init intel_pmu_pebs_data_source_skl(bool pmem) 98 { 99 u64 pmem_or_l4 = pmem ? LEVEL(PMEM) : LEVEL(L4); ... 105 pebs_data_source[0x0d] = OP_LH | LEVEL(ANY_CACHE) | REM | P(SNOOP, HITM); 106 } Which means that it's possible that it's a remote access and the cache level is ANY_CACHE, it's good to add checking for bit PERF_MEM_REMOTE_REMOTE:
u64 remote = data_src->mem_remote;
/* * A hit in another cores cache must mean a llc snoop * filter hit */ if (lnum == P(LVLNUM, ANY_CACHE) && remote != P(REMOTE, REMOTE)) { if (snoop & P(SNOOP, HITM)) HITM_INC(lcl_hitm); } Appreciate German's reviewing and testing, and sorry I jumped in very late.
Thanks, Leo
> + > if (lvl & P(LVL, LOC_RAM) || lnum == P(LVLNUM, RAM)) { > stats->lcl_dram++; > if (snoop & P(SNOOP, HIT)) > -- > 2.32.0 >
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