On Tue, Aug 12, 2014 at 06:45:15PM -0700, Andi Kleen wrote: > From: Andi Kleen <a...@linux.intel.com> > > On Broadwell INST_RETIRED.PREC_DIST cannot be used with any period > that doesn't have the lowest 6 bits cleared. And the period > should not be smaller than 128. > > Add a new callback to enforce this, and set it for Broadwell. > > This is erratum BDM57 and BDM11.
Urgh, this blows.
> +/*
> + * Broadwell:
> + * The INST_RETIRED.ALL period always needs to have lowest
> + * 6bits cleared (BDM57). It shall not use a period smaller
> + * than 100 (BDM11). We combine the two to enforce
> + * a min-period of 128.
> + */
> +static unsigned bdw_limit_period(struct perf_event *event, unsigned left)
> +{
> + if ((event->hw.config & 0xffff) == 0x1c0) {
ISTR we have actual proper defines for that.
> + if (left < 128)
> + left = 128;
> + left &= ~0x3fu;
> + }
> + return left;
> +}
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