Re: [PATCH v14 16/32] x86,fs/resctrl: Introduce event configuration field in struct mon_evt

["Moger, Babu" <babu.moger@amd.com>]

Hi Reinette,

On 6/24/25 18:51, Reinette Chatre wrote:
> Hi Babu,
> 
> On 6/13/25 2:05 PM, Babu Moger wrote:
>> When supported, mbm_assign_mode allows the user to configure events to
>> track specific types of memory transactions.
> 
> Since there is also a "default" mbm_assign_mode this should be made specific
> to mbm_event.
> 
Changed to
"When supported, mbm_event mode allows the user to configure events to
track specific types of memory transactions."


>>
>> Introduce the evt_cfg field in struct mon_evt to define the type of memory
>> transactions tracked by a monitoring event. Also add helper functions to
>> get and set the evt_cfg value.
> 
> hmmm ... this does not sound right (more below)
> 

Removed the resctrl_set_mon_evt_cfg().

Changed to
"Introduce the evt_cfg field in struct mon_evt to define the type of
memory transactions tracked by a monitoring event. Also add a helper
function to get the evt_cfg value."

>>
>> Signed-off-by: Babu Moger <babu.moger@amd.com>
>> ---
>> v14: This is updated patch from previous patch.
>>      https://lore.kernel.org/lkml/95b7f4e9d72773e8fda327fc80b429646efc3a8a.1747349530.git.babu.moger@amd.com/
>>      Removed mbm_mode as it is not required anymore.
>>      Added resctrl_get_mon_evt_cfg() and resctrl_set_mon_evt_cfg().
>>
>> v13: New patch to handle different event configuration types with
>>      mbm_cntr_assign mode.
>> ---
>>  arch/x86/kernel/cpu/resctrl/core.c |  4 ++++
>>  fs/resctrl/internal.h              |  4 ++++
>>  fs/resctrl/monitor.c               | 10 ++++++++++
>>  include/linux/resctrl.h            |  3 +++
>>  4 files changed, 21 insertions(+)
>>
>> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
>> index 01b210febc7d..1df171d04bea 100644
>> --- a/arch/x86/kernel/cpu/resctrl/core.c
>> +++ b/arch/x86/kernel/cpu/resctrl/core.c
>> @@ -875,10 +875,14 @@ static __init bool get_rdt_mon_resources(void)
>>  	}
>>  	if (rdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL) || rdt_cpu_has(X86_FEATURE_ABMC)) {
>>  		resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID);
>> +		resctrl_set_mon_evt_cfg(QOS_L3_MBM_TOTAL_EVENT_ID, MAX_EVT_CONFIG_BITS);
>>  		ret = true;
>>  	}
>>  	if (rdt_cpu_has(X86_FEATURE_CQM_MBM_LOCAL) || rdt_cpu_has(X86_FEATURE_ABMC)) {
>>  		resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID);
>> +		resctrl_set_mon_evt_cfg(QOS_L3_MBM_LOCAL_EVENT_ID,
>> +					READS_TO_LOCAL_MEM | READS_TO_LOCAL_S_MEM |
>> +					NON_TEMP_WRITE_TO_LOCAL_MEM);
>>  		ret = true;
>>  	}
> 
> The architecture should have no business setting the event configuration. This should
> all be managed via resctrl fs, no? I think the resctrl_set_mon_evt_cfg() helper should
> be dropped. The above initialization can be done as part of mon_event_all[] initialization
> within resctrl.
> 
Moved it to resctrl_mon_resource_init().


@@ -926,7 +931,12 @@ int resctrl_mon_resource_init(void)

        if (r->mon.mbm_cntr_assignable) {
                resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID);
+               mon_event_all[QOS_L3_MBM_TOTAL_EVENT_ID].evt_cfg =
MAX_EVT_CONFIG_BITS;
+
                resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID);
+               mon_event_all[QOS_L3_MBM_LOCAL_EVENT_ID].evt_cfg =
READS_TO_LOCAL_MEM |
+
READS_TO_LOCAL_S_MEM |
+
NON_TEMP_WRITE_TO_LOCAL_MEM;
                resctrl_file_fflags_init("num_mbm_cntrs",
                                         RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
                resctrl_file_fflags_init("available_mbm_cntrs",


>>  
>> diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
>> index 20e2c45cea64..71059c2cda16 100644
>> --- a/fs/resctrl/internal.h
>> +++ b/fs/resctrl/internal.h
>> @@ -56,6 +56,9 @@ static inline struct rdt_fs_context *rdt_fc2context(struct fs_context *fc)
>>   * @evtid:		event id
>>   * @rid:		index of the resource for this event
>>   * @name:		name of the event
>> + * @@evt_cfg:		Event configuration value that represents the
> 
> Extra @ in "@@evt_cfg"

Sure.

> 
>> + *			memory transactions (e.g., READS_TO_LOCAL_MEM,
>> + *			READS_TO_REMOTE_MEM) being tracked by @evtid.
> 
> Can append "Only valid if @evtid is an MBM event."

Sure.

> 
>>   * @configurable:	true if the event is configurable
>>   * @enabled:		true if the event is enabled
>>   */
>> @@ -63,6 +66,7 @@ struct mon_evt {
>>  	enum resctrl_event_id	evtid;
>>  	enum resctrl_res_level	rid;
>>  	char			*name;
>> +	u32			evt_cfg;
>>  	bool			configurable;
>>  	bool			enabled;
>>  };
>> diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
>> index 2893da994f3c..3e1a8239b0d3 100644
>> --- a/fs/resctrl/monitor.c
>> +++ b/fs/resctrl/monitor.c
>> @@ -884,6 +884,16 @@ bool resctrl_is_mon_event_enabled(enum resctrl_event_id eventid)
>>  	       mon_event_all[eventid].enabled;
>>  }
>>  
>> +u32 resctrl_get_mon_evt_cfg(enum resctrl_event_id evtid)
>> +{
>> +	return mon_event_all[evtid].evt_cfg;
>> +}
>> +
>> +void resctrl_set_mon_evt_cfg(enum resctrl_event_id evtid, u32 evt_cfg)
>> +{
>> +	mon_event_all[evtid].evt_cfg = evt_cfg;
>> +}
>> +
>>  /**
>>   * resctrl_mon_resource_init() - Initialise global monitoring structures.
>>   *
>> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
>> index 468a4ebabc64..a58dd40b7246 100644
>> --- a/include/linux/resctrl.h
>> +++ b/include/linux/resctrl.h
>> @@ -413,6 +413,9 @@ static inline bool resctrl_is_mbm_event(enum resctrl_event_id eventid)
>>  		eventid <= QOS_L3_MBM_LOCAL_EVENT_ID);
>>  }
>>  
>> +u32 resctrl_get_mon_evt_cfg(enum resctrl_event_id eventid);
>> +void resctrl_set_mon_evt_cfg(enum resctrl_event_id eventid, u32 evt_cfg);
> 
> I think resctrl_set_mon_evt_cfg() should be dropped. Any changes to mon_evt:evt_cfg
> should be via resctrl, either via initialization (all archs should use same default)
> or when user writes to the event configuration's file.

Sure.

> 
>> +
>>  #define for_each_mbm_event_id(eventid)				\
>>  	for (eventid = QOS_L3_MBM_TOTAL_EVENT_ID;		\
>>  	     eventid <= QOS_L3_MBM_LOCAL_EVENT_ID; eventid++)
> 
> sidenote: This change looks to be a good foundation to bring back the BMEC optimization
> you worked on earlier where it is no longer needed to read event configuration from
> hardware.
> 

Yes. Sure. Will work on it later.

-- 
Thanks
Babu Moger