lkml.org 
[lkml]   [2022]   [Mar]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 4/7] perf/x86/amd/core: Detect available counters
On Thu, Mar 17, 2022 at 11:58:33AM +0530, Sandipan Das wrote:
> If AMD Performance Monitoring Version 2 (PerfMonV2) is
> supported, use CPUID Fn80000022[EBX] to detect the number
> of Core PMCs. This offers more flexibility if the counts
> change across processor families.
>
> Signed-off-by: Sandipan Das <sandipan.das@amd.com>
> ---
> arch/x86/events/amd/core.c | 5 +++++
> arch/x86/include/asm/perf_event.h | 8 ++++++++
> 2 files changed, 13 insertions(+)
>
> diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
> index a074af97faa9..05d79afe5173 100644
> --- a/arch/x86/events/amd/core.c
> +++ b/arch/x86/events/amd/core.c
> @@ -980,9 +980,14 @@ static int __init amd_core_pmu_init(void)
>
> /* Check for Performance Monitoring v2 support */
> if (boot_cpu_has(X86_FEATURE_PERFMON_V2)) {
> + int ebx = cpuid_ebx(EXT_PERFMON_DEBUG_FEATURES);
> +
> /* Update PMU version for later usage */
> x86_pmu.version = 2;
>
> + /* Find the number of available Core PMCs */
> + x86_pmu.num_counters = EXT_PERFMON_DEBUG_NUM_CORE_PMC(ebx);
> +
> amd_pmu_global_cntr_mask = (1ULL << x86_pmu.num_counters) - 1;
> }

I prefer using unions like cpuid10_ebx. Such much easier to read than
all this shouting.

\
 
 \ /
  Last update: 2022-03-17 12:33    [W:0.214 / U:0.024 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site