On 01/08/2019 10:08 PM, Liang, Kan wrote:
On 1/8/2019 1:13 AM, Wei Wang wrote:
On 01/07/2019 10:22 PM, Liang, Kan wrote:
Thanks for sharing. I understand the point of maintaining those
models at one place,
but this factor-out doesn't seem very elegant to me, like below
__intel_pmu_init (int model, struct x86_pmu *x86_pmu)
{
...
switch (model)
case INTEL_FAM6_NEHALEM:
case INTEL_FAM6_NEHALEM_EP:
case INTEL_FAM6_NEHALEM_EX:
intel_pmu_lbr_init(x86_pmu);
if (model != boot_cpu_data.x86_model)
return;
/* Other a lot of things init like below..*/
memcpy(hw_cache_event_ids, nehalem_hw_cache_event_ids,
sizeof(hw_cache_event_ids));
memcpy(hw_cache_extra_regs, nehalem_hw_cache_extra_regs,
sizeof(hw_cache_extra_regs));
x86_pmu.event_constraints = intel_nehalem_event_constraints;
x86_pmu.pebs_constraints =
intel_nehalem_pebs_event_constraints;
x86_pmu.enable_all = intel_pmu_nhm_enable_all;
x86_pmu.extra_regs = intel_nehalem_extra_regs;
...
Case...
}
We need insert "if (model != boot_cpu_data.x86_model)" in every
"Case xx".
What would be the rationale that we only do lbr_init for "x86_pmu"
when model != boot_cpu_data.x86_model?
(It looks more like a workaround to factor-out the function and get
what we want)
I thought the new function may be extended to support fake pmu as
below.
It's not only for lbr. PMU has many CPU specific features. It can be
used for other features, if you want to check the compatibility in
future. But I don't have an example now.
__intel_pmu_init (int model, struct x86_pmu *x86_pmu)
{
bool fake_pmu = (model != boot_cpu_data.x86_model) ? true : false;
...
switch (model)
case INTEL_FAM6_NEHALEM:
case INTEL_FAM6_NEHALEM_EP:
case INTEL_FAM6_NEHALEM_EX:
intel_pmu_lbr_init(x86_pmu);
x86_pmu->event_constraints = intel_nehalem_event_constraints;
x86_pmu->pebs_constraints = intel_nehalem_pebs_event_constraints;
x86_pmu->enable_all = intel_pmu_nhm_enable_all;
x86_pmu->extra_regs = intel_nehalem_extra_regs;
if (fake_pmu)
return;
It looks similar as the one I shared above, the difference is that
more things
(e.g. constraints) are assigned to x86_fake_pmu.
I'm not sure about the logic behind it (still look like a workaround).
The fake x86_pmu will include all the supported features in host. If
you want to check other features in future, it would be useful.
OK, I'll think more about if we could have a cleaner way to factor out this.
Best,
Wei
