linux-kernel - Re: [PATCH v10 13/13] Documentation/x86: Update resctrl.rst for new features

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Message-ID: <50e99ce9-40d4-5806-f2e0-57a685db36ea@amd.com>
Date:   Thu, 5 Jan 2023 10:06:03 -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,
        christophe.leroy@...roup.eu, jarkko@...nel.org,
        adrian.hunter@...el.com, quic_jiles@...cinc.com,
        peternewman@...gle.com
Subject: Re: [PATCH v10 13/13] Documentation/x86: Update resctrl.rst for new
 features

Hi Reinette,

On 1/4/23 18:30, Reinette Chatre wrote:
> Hi Babu,
>
> On 12/22/2022 3:31 PM, Babu Moger wrote:
>> Update the documentation for the new features:
>> 1. Slow Memory Bandwidth allocation (SMBA).
>>    With this feature, the QOS  enforcement policies can be applied
>>    to the external slow memory connected to the host. QOS enforcement
>>    is accomplished by assigning a Class Of Service (COS) to a processor
>>    and specifying allocations or limits for that COS for each resource
>>    to be allocated.
>>
>> 2. Bandwidth Monitoring Event Configuration (BMEC).
>>    The bandwidth monitoring events mbm_total_bytes and mbm_local_bytes
>>    are set to count all the total and local reads/writes respectively.
>>    With the introduction of slow memory, the two counters are not
>>    enough to count all the different types of memory events. With the
>>    feature BMEC, the users have the option to configure mbm_total_bytes
>>    and mbm_local_bytes to count the specific type of events.
>>
>> Also add configuration instructions with examples.
>>
>> Signed-off-by: Babu Moger <babu.moger@....com>
>> ---
>>  Documentation/x86/resctrl.rst | 141 +++++++++++++++++++++++++++++++++-
>>  1 file changed, 139 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/x86/resctrl.rst b/Documentation/x86/resctrl.rst
>> index 71a531061e4e..bea6cab06873 100644
>> --- a/Documentation/x86/resctrl.rst
>> +++ b/Documentation/x86/resctrl.rst
>> @@ -17,14 +17,16 @@ AMD refers to this feature as AMD Platform Quality of Service(AMD QoS).
>>  This feature is enabled by the CONFIG_X86_CPU_RESCTRL and the x86 /proc/cpuinfo
>>  flag bits:
>>  
>> -=============================================	================================
>> +===============================================	================================
>>  RDT (Resource Director Technology) Allocation	"rdt_a"
>>  CAT (Cache Allocation Technology)		"cat_l3", "cat_l2"
>>  CDP (Code and Data Prioritization)		"cdp_l3", "cdp_l2"
>>  CQM (Cache QoS Monitoring)			"cqm_llc", "cqm_occup_llc"
>>  MBM (Memory Bandwidth Monitoring)		"cqm_mbm_total", "cqm_mbm_local"
>>  MBA (Memory Bandwidth Allocation)		"mba"
>> -=============================================	================================
>> +SMBA (Slow Memory Bandwidth Allocation)         "smba"
>> +BMEC (Bandwidth Monitoring Event Configuration) "bmec"
>> +===============================================	================================
>>  
>>  To use the feature mount the file system::
>>  
>> @@ -161,6 +163,82 @@ with the following files:
>>  "mon_features":
>>  		Lists the monitoring events if
>>  		monitoring is enabled for the resource.
>> +		Example::
>> +
>> +			# cat /sys/fs/resctrl/info/L3_MON/mon_features
>> +			llc_occupancy
>> +			mbm_total_bytes
>> +			mbm_local_bytes
>> +
>> +		If the system supports Bandwidth Monitoring Event
>> +		Configuration (BMEC), then the bandwidth events will
>> +		be configurable. The output will be::
>> +
>> +			# 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
>> +
>> +"mbm_total_bytes_config", "mbm_local_bytes_config":
>> +	Read/write files containing the configuration for the mbm_total_bytes
>> +	and mbm_local_bytes events, respectively, when the Bandwidth
>> +	Monitoring Event Configuration (BMEC) feature is supported.
>> +	The event configuration settings are domain specific and affect
>> +	all the CPUs in the domain. When an event configuration is changed,
>> +	the bandwidth counters for all the RMIDs and the events will be
>> +	cleared for that domain. The next read for every RMID will report
> I think it needs to be emphasized that configuring one event impacts
> all events. How about (please feel free to change): "When either event
> configuration is changed, the bandwidth counters for all RMIDs of both
> events (mbm_total_bytes as well as mbm_local_bytes) are cleared for that
> domain. The next read ..."

Sure. will change it.

Thanks

Babu

>
>> +	"Unavailable" and subsequent reads will report the valid value.
>> +
>
> Reinette

-- 
Thanks
Babu Moger