linux-kernel - Re: [PATCH v8 07/13] x86/resctrl: Introduce data structure to support monitor configuration

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Date:   Wed, 23 Nov 2022 12:23:53 -0600
From:   "Moger, Babu" <babu.moger@....com>
To:     Reinette Chatre <reinette.chatre@...el.com>, corbet@....net,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de
Cc:     fenghua.yu@...el.com, dave.hansen@...ux.intel.com, x86@...nel.org,
        hpa@...or.com, paulmck@...nel.org, akpm@...ux-foundation.org,
        quic_neeraju@...cinc.com, rdunlap@...radead.org,
        damien.lemoal@...nsource.wdc.com, songmuchun@...edance.com,
        peterz@...radead.org, jpoimboe@...nel.org, pbonzini@...hat.com,
        chang.seok.bae@...el.com, pawan.kumar.gupta@...ux.intel.com,
        jmattson@...gle.com, daniel.sneddon@...ux.intel.com,
        sandipan.das@....com, tony.luck@...el.com, james.morse@....com,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        bagasdotme@...il.com, eranian@...gle.com
Subject: Re: [PATCH v8 07/13] x86/resctrl: Introduce data structure to support
 monitor configuration

Hi Reinette,

On 11/22/22 18:14, Reinette Chatre wrote:
> Hi Babu,
>
> On 11/4/2022 1:00 PM, Babu Moger wrote:
>> Add a new field in mon_evt to support Bandwidth Monitoring Event
>> Configuration(BMEC) and also update the "mon_features" display.
>>
>> The sysfs file "mon_features" will display the monitor configuration
> sysfs -> resctrl ?
Sure.
>
>> if supported.
> This is not clear. "mon_features" does not display the monitor
> configuration, it displays the name of the file that can be used to 
> see the monitor configuration.

Will change it to:

The sysfs -> resctrl file "mon_features" will display the supported events
and files that can be used to configure those events if monitor
configuration is supported.


>
>> Before the change.
>> 	$cat /sys/fs/resctrl/info/L3_MON/mon_features
>> 	llc_occupancy
>> 	mbm_total_bytes
>> 	mbm_local_bytes
>>
>> After the change when BMEC is supported.
>> 	$cat /sys/fs/resctrl/info/L3_MON/mon_features
>> 	llc_occupancy
>> 	mbm_total_bytes
>> 	mbm_total_bytes_config
>> 	mbm_local_bytes
>> 	mbm_local_bytes_config
>>
>> Signed-off-by: Babu Moger <babu.moger@....com>
>> ---
>>  arch/x86/kernel/cpu/resctrl/internal.h |    2 ++
>>  arch/x86/kernel/cpu/resctrl/monitor.c  |    6 ++++++
>>  arch/x86/kernel/cpu/resctrl/rdtgroup.c |    5 ++++-
>>  3 files changed, 12 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
>> index e30e8b23f6b5..5459b5022760 100644
>> --- a/arch/x86/kernel/cpu/resctrl/internal.h
>> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
>> @@ -63,11 +63,13 @@ DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key);
>>   * struct mon_evt - Entry in the event list of a resource
>>   * @evtid:		event id
>>   * @name:		name of the event
>> + * @configurable:	true if the event is configurable
>>   * @list:		entry in &rdt_resource->evt_list
>>   */
>>  struct mon_evt {
>>  	enum resctrl_event_id	evtid;
>>  	char			*name;
>> +	bool			configurable;
>>  	struct list_head	list;
>>  };
>>  
>> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
>> index efe0c30d3a12..06c2dc980855 100644
>> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
>> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
>> @@ -750,6 +750,7 @@ int rdt_get_mon_l3_config(struct rdt_resource *r)
>>  {
>>  	unsigned int mbm_offset = boot_cpu_data.x86_cache_mbm_width_offset;
>>  	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
>> +	bool mon_configurable = rdt_cpu_has(X86_FEATURE_BMEC);
>>  	unsigned int threshold;
>>  	int ret;
>>  
>> @@ -783,6 +784,11 @@ int rdt_get_mon_l3_config(struct rdt_resource *r)
>>  	if (ret)
>>  		return ret;
>>  
>> +	if (mon_configurable) {
>> +		mbm_total_event.configurable = true;
>> +		mbm_local_event.configurable = true;
>> +	}
>> +
> Is the local variable needed? Why not just:
> 	if (rdt_cpu_has(X86_FEATURE_BMEC))


Local variable not requited. Will change it.

Thanks

Babu

>
>
> Reinette

-- 
Thanks
Babu Moger