linux-kernel - Re: [PATCH] perf/x86/zhaoxin: Fix instructions error by missing fixedctr member

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Message-ID: <a6cd3756-5aa7-435f-9ee7-3fde67c29f17@linux.intel.com>
Date: Thu, 19 Jun 2025 10:33:01 -0400
From: "Liang, Kan" <kan.liang@...ux.intel.com>
To: tanze <tanze@...inos.cn>, peterz@...radead.org
Cc: linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
 x86@...nel.org
Subject: Re: [PATCH] perf/x86/zhaoxin: Fix instructions error by missing
 fixedctr member



On 2025-06-18 11:19 p.m., tanze wrote:
> Perf's instructions event tests on Zhaoxin CPUs may exhibit:
> 
>   $perf stat -e instructions,cycles ls -l
> 
>   ......
>   Performance counter stats for 'ls -l':
> 
>                  0      instructions                     #    0.00  insn per cycle
>          9,488,278      cycles
> 
>        0.004365407 seconds time elapsed
> 
>        0.003303000 seconds user
>        0.001099000 seconds sys
> 
> The absence of the fixedctr member leads to an incorrect hwc->event_base
> value on Zhaoxin CPUs, causing a discrepancy in the instruction count
> reported by perf stat. This commit resolves the instruction count issue
> by properly initializing the fixedctr member.
> 
> Fixes: 149fd4712bcd ("perf/x86/intel: Support Perfmon MSRs aliasing")
> 

Please remove the empty line.

> Signed-off-by: tanze <tanze@...inos.cn>

I have no idea Zhaoxin also have fixed counters.
If so, Yes, I think the patch is required.

Reviewed-by: Kan Liang <kan.liang@...ux.intel.com>

Thanks,
Kan> ---
>  arch/x86/events/zhaoxin/core.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/x86/events/zhaoxin/core.c b/arch/x86/events/zhaoxin/core.c
> index 4bdfcf091200..3fc3f9abece9 100644
> --- a/arch/x86/events/zhaoxin/core.c
> +++ b/arch/x86/events/zhaoxin/core.c
> @@ -467,6 +467,7 @@ static const struct x86_pmu zhaoxin_pmu __initconst = {
>  	.schedule_events	= x86_schedule_events,
>  	.eventsel		= MSR_ARCH_PERFMON_EVENTSEL0,
>  	.perfctr		= MSR_ARCH_PERFMON_PERFCTR0,
> +	.fixedctr		= MSR_ARCH_PERFMON_FIXED_CTR0,
>  	.event_map		= zhaoxin_pmu_event_map,
>  	.max_events		= ARRAY_SIZE(zx_pmon_event_map),
>  	.apic			= 1,