Messages in this thread | | | Date | Thu, 21 Jun 2012 15:47:49 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [tip:perf/core] perf/x86: Add generic Intel uncore PMU support |
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On 06/21/2012 03:43 PM, Andrew Morton wrote: > > Regardless of that, we have some head-scratching to do: > > > #define UNCORE_PMU_HRTIMER_INTERVAL (60 * NSEC_PER_SEC) > > and > > #define NSEC_PER_SEC 1000000000L > > and 60 billion doesn't fit in 32 bits. So do we fix the > perf_event_intel_uncore.c callsites? Or do we fix the > UNCORE_PMU_HRTIMER_INTERVAL definition? Or do we fix the NSEC_PER_SEC > definition? > > I'm thinking perhaps the latter. What *is* the type of a nanosecond in > Linux? include/linux/ktime.h is pretty insistent that it is u64. If > so, NSEC_PER_SEC should logically have type ULL. But changing both its > size and signedness is a pretty big change.
We could change the size only. The range from 9223372036.854775808 to 18446744073.709551615 seconds (292-584 years) isn't really that significant.
-hpa
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