linux-kernel - Re: [PATCH v3] perf/x86/zhaoxin: Fix instructions error by missing fixedctr member

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Message-ID: <5dee24f7-fc92-44f9-9a21-799a8ae20315@kylinos.cn>
Date: Wed, 15 Oct 2025 16:55:37 +0800
From: tanze <tanze@...inos.cn>
To: "Mi, Dapeng" <dapeng1.mi@...ux.intel.com>, peterz@...radead.org,
 kan.liang@...ux.intel.com
Cc: linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
 x86@...nel.org
Subject: Re: [PATCH v3] perf/x86/zhaoxin: Fix instructions error by missing
 fixedctr member

Hi Dapeng,

在 2025/9/30 10:49, Mi, Dapeng 写道:
> 
> On 6/20/2025 10:37 AM, 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")
>> Signed-off-by: tanze <tanze@...inos.cn>
>> Reviewed-by: Kan Liang <kan.liang@...ux.intel.com>
>> ---
>>   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,
> 
> LGTM.
> 
> Reviewed-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>

Thank You
Ze Tan