From: Andi Kleen <a...@linux.intel.com> Add a instructions-p event alias that uses the PDIR randomized instruction retirement event. This is useful to avoid some systematic sampling shadow problems. Normally PEBS sampling has a systematic shadow. With PDIR enabled the hardware adds some randomization that statistically avoids this problem. In this sense, it's more precise over a whole sampling interval, but an individual sample can be less precise. But since we sample overall it's a more precise event.
This could be used before using the explicit event code syntax, but it's easier and more user friendly to use with an "instructions-p" alias. I expect this will eventually become a common use case. Right now for Haswell, will add to Ivy Bridge later too. Signed-off-by: Andi Kleen <a...@linux.intel.com> --- arch/x86/kernel/cpu/perf_event_intel.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c index e9706f0..707fd5c 100644 --- a/arch/x86/kernel/cpu/perf_event_intel.c +++ b/arch/x86/kernel/cpu/perf_event_intel.c @@ -2098,6 +2098,7 @@ PMU_EVENT(cycles_t, "cycles-t", "event=0x3c,intx=1"); PMU_EVENT(cycles_ct, "cycles-ct", "event=0x3c,intx=1,intx_cp=1"); PMU_EVENT(insns_t, "instructions-t", "event=0xc0,intx=1"); PMU_EVENT(insns_ct, "instructions-ct","event=0xc0,intx=1,intx_cp=1"); +PMU_EVENT(insns_prec, "instructions-p", "event=0xc0,umask=0x01,precise=2"); #define PMU_EVENT_PTR(x) &attr_ ## x .attr.attr @@ -2120,6 +2121,7 @@ static struct attribute *hsw_events_attrs[] = { PMU_EVENT_PTR(cycles_ct), PMU_EVENT_PTR(insns_t), PMU_EVENT_PTR(insns_ct), + PMU_EVENT_PTR(insns_prec), NULL }; -- 1.7.7.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/