Re: [Patch v1 04/10] perf/x86: add memory profiling via PEBS Load Latency

Peter Zijlstra
2012-10-29T15:35:27Z

On Mon, 2012-10-29 at 16:15 +0100, Stephane Eranian wrote:
> +static u64 load_latency_data(u64 status)
> +{
> + union intel_x86_pebs_dse dse;
> + u64 val;
> + int model = boot_cpu_data.x86_model;
> + int fam = boot_cpu_data.x86;
> +
> + dse.val = status;
> +
> + /*
> + * use the mapping table for bit 0-15
> + */
> + val = pebs_data_source[dse.ld_dse];
> +
> + /*
> + * Nehalem models do not support TLB, Lock infos
> + */
> + if (fam == 0x6 && (model == 26 || model == 30
> + || model == 31 || model == 46)) {
> + val |= P(TLB, NA) | P(LOCK, NA);
> + return val;
> + }

I'm so 100% sure we'll forget to add a nhm model number if we ever find
we missed one.

Could we either add a classification enum to x86_pmu that is set in the
big model switch on init, or do this with your new constraints flags,
where we have a different flag for NHM_LL vs SNB_LL or so?

Or if all else fails, add a quirk to the Intel Debugstore bits bitfield,
something like pebs_ll_nhm.

> + /*
> + * bit 4: TLB access
> + * 0 = did not miss 2nd level TLB
> + * 1 = missed 2nd level TLB
> + */
> + if (dse.ld_stlb_miss)
> + val |= P(TLB, MISS) | P(TLB, L2);
> + else
> + val |= P(TLB, HIT) | P(TLB,L1) | P(TLB, L2);
> +
> + /*
> + * bit 5: locked prefix
> + */
> + if (dse.ld_locked)
> + val |= P(LOCK, LOCKED);
> +
> + return val;
> +}