On 3/11/2021 11:32 AM, Peter Zijlstra wrote:
On Thu, Mar 11, 2021 at 05:09:25PM +0100, Peter Zijlstra wrote:
On Wed, Mar 10, 2021 at 08:37:56AM -0800, kan.li...@linux.intel.com wrote:
From: Kan Liang <kan.li...@linux.intel.com>
Alder Lake Hybrid system has two different types of core, Golden Cove
core and Gracemont core. The Golden Cove core is registered to
"cpu_core" PMU. The Gracemont core is registered to "cpu_atom" PMU.
The difference between the two PMUs include:
- Number of GP and fixed counters
- Events
- The "cpu_core" PMU supports Topdown metrics.
The "cpu_atom" PMU supports PEBS-via-PT.
The "cpu_core" PMU is similar to the Sapphire Rapids PMU, but without
PMEM.
The "cpu_atom" PMU is similar to Tremont, but with different
event_constraints, extra_regs and number of counters.
+ /* Initialize big core specific PerfMon capabilities.*/
+ pmu = &x86_pmu.hybrid_pmu[X86_HYBRID_PMU_CORE_IDX];
+ pmu->name = "cpu_core";
+ /* Initialize Atom core specific PerfMon capabilities.*/
+ pmu = &x86_pmu.hybrid_pmu[X86_HYBRID_PMU_ATOM_IDX];
+ pmu->name = "cpu_atom";
So do these things use the same event lists as SPR and TNT? Is there any
way to discover that, because AFAICT /proc/cpuinfo will say every CPU
is 'Alderlake', and the above also doesn't give any clue.
FWIW, ARM big.LITTLE does discriminate in its /proc/cpuinfo, but I'm not
entirely sure it's really useful. Mark said perf userspace uses
somethink akin to our CPUID, except exposed through sysfs, to find the
event lists.
My desktop has: cpu/caps/pmu_name and that gives "skylake", do we want
the above to have cpu_core/caps/pmu_name give "sapphire_rapids" etc.. ?
FWIW, "Tremont" is the only pmu_name with a capital :-( I don't suppose
we can still fix that?
The cpu/caps/pmu_name is not used for the event list.
I don't think perf tool checks the "Tremont". I think it should be OK to
fix it. Let me post a patch.
Thanks,
Kan
