Messages in this thread Patch in this message | | | Subject | Re: [PATCH 4/9] perf/x86/intel: Support hardware TopDown metrics | From | "Liang, Kan" <> | Date | Tue, 4 Jun 2019 16:39:08 -0400 |
| |
On 5/29/2019 12:58 PM, Peter Zijlstra wrote: > On Wed, May 29, 2019 at 10:42:10AM -0400, Liang, Kan wrote: >> On 5/29/2019 3:54 AM, Peter Zijlstra wrote: > >>> cd09c0c40a97 ("perf events: Enable raw event support for Intel unhalted_reference_cycles event") >>> >>> We used the fake event=0x00, umask=0x03 for CPU_CLK_UNHALTED.REF_TSC, >>> because that was not available as a generic event, *until now* it seems. >>> I see ICL actually has it as a generic event, which means we need to fix >>> up the constraint mask for that differently. >>> >> >> There is no change for REF_TSC on ICL. > > Well, if I look at the SDM for May'19 (latest afaict), Volume 3, Chapter > 19.3 'Performance Monitoring Events for Future Intel (C) Core(tm) > Processors' the table lists: > > Event Num. Umask Value Event Mask Mnemonic > > 00H 03H CPU_CLK_UNHALTED.REF_TSC > > as a generic event, without constraints, unlike any of the preceding > uarchs, where that event was not available except through FIXED2. > > That is most certainly a change.
I checked with our internal team. They confirmed that there is no change for REF_TSC on ICL. They will fix the comment in the next SDM update. Thanks for bringing this up.
> >>> But note that for all previous uarchs this event did not in fact exist. >>> >>> It appears the TOPDOWN.SLOTS thing, which is available in in FIXED3 is >>> event=0x00, umask=0x04, is indeed a generic event too. >> >> The SLOTS do have a generic event, TOPDOWN.SLOTS_P, event=0xA4, umask=0x1. >> >> I think we need a fix as below for ICL, so the SLOT event can be extended to >> generic event. >> - FIXED_EVENT_CONSTRAINT(0x0400, 3), /* SLOTS */ >> + FIXED_EVENT_CONSTRAINT(0x01a4, 3), /* TOPDOWN.SLOTS */ > > Then WTH is that 00H, 04H event listed in the table? Note the distinct > lack of 'Fixed Counter' or any other contraints in the 'Comments' > column. >
TOPDOWN.SLOTS(0x0400) is only available on FIXED3. It's not a generic event. The equivalent event for GP counters is TOPDOWN.SLOTS_P (0x01a4). But it's not architectural event. So I think the best way is to force TOPDOWN.SLOTS(0x0400) only in FIXED3. The patch as below will do so.
From 22e3ed25340e4f46685a059cf2184747a3e02a47 Mon Sep 17 00:00:00 2001 From: Kan Liang <kan.liang@linux.intel.com> Date: Tue, 4 Jun 2019 10:36:08 -0700 Subject: [PATCH] perf/x86/intel: Set correct mask for TOPDOWN.SLOTS
TOPDOWN.SLOTS(0x0400) is not a generic event. It is only available on fixed counter3.
Don't extend its mask to generic counters.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com> --- arch/x86/events/intel/core.c | 6 ++++-- arch/x86/include/asm/perf_event.h | 5 +++++ 2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index 4377bf6a6f82..f30d02830921 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -5066,12 +5066,14 @@ __init int intel_pmu_init(void)
if (x86_pmu.event_constraints) { /* - * event on fixed counter2 (REF_CYCLES) only works on this + * event on fixed counter2 (REF_CYCLES) and + * fixed counter3 (TOPDOWN.SLOTS) only work on this * counter, so do not extend mask to generic counters */ for_each_event_constraint(c, x86_pmu.event_constraints) { if (c->cmask == FIXED_EVENT_FLAGS - && c->idxmsk64 != INTEL_PMC_MSK_FIXED_REF_CYCLES) { + && c->idxmsk64 != INTEL_PMC_MSK_FIXED_REF_CYCLES + && c->idxmsk64 != INTEL_PMC_MSK_FIXED_SLOTS) { c->idxmsk64 |= (1ULL << x86_pmu.num_counters) - 1; } c->idxmsk64 &= diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h index 1392d5e6e8d6..457d35a75ad3 100644 --- a/arch/x86/include/asm/perf_event.h +++ b/arch/x86/include/asm/perf_event.h @@ -167,6 +167,11 @@ struct x86_pmu_capability { #define INTEL_PMC_IDX_FIXED_REF_CYCLES (INTEL_PMC_IDX_FIXED + 2) #define INTEL_PMC_MSK_FIXED_REF_CYCLES (1ULL << INTEL_PMC_IDX_FIXED_REF_CYCLES)
+/* TOPDOWN.SLOTS: */ +#define MSR_ARCH_PERFMON_FIXED_CTR3 0x30c +#define INTEL_PMC_IDX_FIXED_SLOTS (INTEL_PMC_IDX_FIXED + 3) +#define INTEL_PMC_MSK_FIXED_SLOTS (1ULL << INTEL_PMC_IDX_FIXED_SLOTS) + /* * We model BTS tracing as another fixed-mode PMC. * -- 2.14.5 Thanks, Kan
| |