Re: [PATCH v15 27/34] fs/resctrl: Provide interface to update the event configurations

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

Hi Reinette,

On 7/17/2025 10:55 PM, Reinette Chatre wrote:
> Hi Babu,
> 
> On 7/8/25 3:17 PM, Babu Moger wrote:
>> When "mbm_event" counter assignment mode is supported, users can modify
>> the event configuration by writing to the 'event_filter' resctrl file.
>> The event configurations for mbm_event mode are located in
>> /sys/fs/resctrl/info/L3_MON/event_configs/.
>>
>> Update the assignments of all CTRL_MON and MON resource groups when the
>> event configuration is modified.
>>
>> Example:
>> $ mount -t resctrl resctrl /sys/fs/resctrl
>>
>> $ cd /sys/fs/resctrl/
>>
>> $ cat info/L3_MON/event_configs/mbm_local_bytes/event_filter
>>    local_reads,local_non_temporal_writes,local_reads_slow_memory
>>
>> $ echo "local_reads,local_non_temporal_writes" >
>>    info/L3_MON/event_configs/mbm_total_bytes/event_filter
>>
>> $ cat info/L3_MON/event_configs/mbm_total_bytes/event_filter
>>    local_reads,local_non_temporal_writes
>>
>> Signed-off-by: Babu Moger <babu.moger@amd.com>
>> ---
> 
> ...
> 
>> ---
>>   Documentation/filesystems/resctrl.rst | 12 +++++
>>   fs/resctrl/internal.h                 |  1 +
>>   fs/resctrl/monitor.c                  | 44 ++++++++++++++++
>>   fs/resctrl/rdtgroup.c                 | 74 ++++++++++++++++++++++++++-
>>   4 files changed, 130 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
>> index 57fd12f0aeca..06c8c08d0341 100644
>> --- a/Documentation/filesystems/resctrl.rst
>> +++ b/Documentation/filesystems/resctrl.rst
>> @@ -342,6 +342,18 @@ with the following files:
>>   	  # cat /sys/fs/resctrl/info/L3_MON/event_configs/mbm_local_bytes/event_filter
>>   	  local_reads,local_non_temporal_writes,local_reads_slow_memory
>>   
>> +	Modify the event configuration by writing to the "event_filter" file within
>> +	the "event_configs" directory. The read/write "event_filter" file contains the
>> +	configuration of the event that reflects which memory transactions are counted by it.
>> +
>> +	For example::
>> +
>> +	  # echo "local_reads, local_non_temporal_writes" >
>> +	    /sys/fs/resctrl/info/L3_MON/event_configs/mbm_total_bytes/event_filter
>> +
>> +	  # cat /sys/fs/resctrl/info/L3_MON/event_configs/mbm_total_bytes/event_filter
>> +	   local_reads,local_non_temporal_writes
>> +
>>   "max_threshold_occupancy":
>>   		Read/write file provides the largest value (in
>>   		bytes) at which a previously used LLC_occupancy
>> diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
>> index b107874407b2..b42890fd937a 100644
>> --- a/fs/resctrl/internal.h
>> +++ b/fs/resctrl/internal.h
>> @@ -409,6 +409,7 @@ void rdtgroup_unassign_cntr_event(struct rdt_mon_domain *d, struct rdtgroup *rdt
>>   				  struct mon_evt *mevt);
>>   int mbm_cntr_get(struct rdt_resource *r, struct rdt_mon_domain *d,
>>   		 struct rdtgroup *rdtgrp, enum resctrl_event_id evtid);
>> +void resctrl_update_cntr_allrdtgrp(struct mon_evt *mevt);
>>   
>>   #ifdef CONFIG_RESCTRL_FS_PSEUDO_LOCK
>>   int rdtgroup_locksetup_enter(struct rdtgroup *rdtgrp);
>> diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
>> index 787dce934903..0722e72f6cb1 100644
>> --- a/fs/resctrl/monitor.c
>> +++ b/fs/resctrl/monitor.c
>> @@ -1173,3 +1173,47 @@ void rdtgroup_unassign_cntr_event(struct rdt_mon_domain *d, struct rdtgroup *rdt
>>   		rdtgroup_free_config_cntr(r, d, rdtgrp, mevt->evtid);
>>   	}
>>   }
>> +
>> +/*
>> + * rdtgroup_update_cntr_event - Update the counter assignments for the event
>> + *				in a group.
>> + * @r:		Resource to which update needs to be done.
>> + * @rdtgrp:	Resctrl group.
>> + * @mevt:	MBM monitor event.
> 
> @mevt needs update match actual parameter

Sure.

> 
>> + */
>> +static void rdtgroup_update_cntr_event(struct rdt_resource *r, struct rdtgroup *rdtgrp,
>> +				       enum resctrl_event_id evtid)
>> +{
>> +	struct rdt_mon_domain *d;
>> +	int cntr_id;
>> +
>> +	list_for_each_entry(d, &r->mon_domains, hdr.list) {
>> +		cntr_id = mbm_cntr_get(r, d, rdtgrp, evtid);
>> +		if (cntr_id >= 0)
>> +			resctrl_arch_config_cntr(r, d, evtid, rdtgrp->mon.rmid,
>> +						 rdtgrp->closid, cntr_id, true);
>> +	}
>> +}
>> +
>> +/*
>> + * resctrl_update_cntr_allrdtgrp - Update the counter assignments for the event
>> + *				   for all the groups.
>> + * @r:		Resource to which update needs to be done.
> 
> @r no longer a parameter
> 

Removed it.

>> + * @mevt	MBM Monitor event.
>> + */
>> +void resctrl_update_cntr_allrdtgrp(struct mon_evt *mevt)
>> +{
>> +	struct rdt_resource *r = resctrl_arch_get_resource(mevt->rid);
>> +	struct rdtgroup *prgrp, *crgrp;
>> +
>> +	/*
>> +	 * Find all the groups where the event is assigned and update
>> +	 * the assignment
> 
> "update the assignment" -> "update the configuration of existing assignments" ?
> 

Sure.

>> +	 */
>> +	list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
>> +		rdtgroup_update_cntr_event(r, prgrp, mevt->evtid);
>> +
>> +		list_for_each_entry(crgrp, &prgrp->mon.crdtgrp_list, mon.crdtgrp_list)
>> +			rdtgroup_update_cntr_event(r, crgrp, mevt->evtid);
>> +	}
>> +}
>> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
>> index bb28ef7e4600..4889e7556cc7 100644
>> --- a/fs/resctrl/rdtgroup.c
>> +++ b/fs/resctrl/rdtgroup.c
>> @@ -1916,6 +1916,77 @@ static int event_filter_show(struct kernfs_open_file *of, struct seq_file *seq,
>>   	return 0;
>>   }
>>   
>> +static int resctrl_process_configs(char *tok, u32 *val)
> 
> Please move to monitor.c and give more specific name. Perhaps
> resctrl_parse_mem_transactions()? Open to ideas.

Sure.
> 
>> +{
>> +	u32 temp_val = 0;
>> +	char *evt_str;
>> +	bool found;
>> +	int i;
>> +
>> +next_config:
>> +	if (!tok || tok[0] == '\0') {
>> +		*val = temp_val;
>> +		return 0;
>> +	}
>> +
>> +	/* Start processing the strings for each memory transaction type */
>> +	evt_str = strim(strsep(&tok, ","));
>> +	found = false;
>> +	for (i = 0; i < NUM_MBM_TRANSACTIONS; i++) {
>> +		if (!strcmp(mbm_transactions[i].name, evt_str)) {
>> +			temp_val |= mbm_transactions[i].val;
>> +			found = true;
>> +			break;
>> +		}
>> +	}
>> +
>> +	if (!found) {
>> +		rdt_last_cmd_printf("Invalid memory transaction type %s\n", evt_str);
>> +		return -EINVAL;
>> +	}
>> +
>> +	goto next_config;
>> +}
>> +
>> +static ssize_t event_filter_write(struct kernfs_open_file *of, char *buf,
>> +				  size_t nbytes, loff_t off)
>> +{
>> +	struct mon_evt *mevt = rdt_kn_parent_priv(of->kn);
>> +	struct rdt_resource *r;
>> +	u32 evt_cfg = 0;
>> +	int ret = 0;
>> +
>> +	/* Valid input requires a trailing newline */
>> +	if (nbytes == 0 || buf[nbytes - 1] != '\n')
>> +		return -EINVAL;
>> +
>> +	buf[nbytes - 1] = '\0';
>> +
>> +	cpus_read_lock();
>> +	mutex_lock(&rdtgroup_mutex);
>> +
>> +	rdt_last_cmd_clear();
>> +
>> +	r = resctrl_arch_get_resource(mevt->rid);
>> +	if (!resctrl_arch_mbm_cntr_assign_enabled(r)) {
>> +		rdt_last_cmd_puts("mbm_event counter assignment mode is not enabled\n");
>> +		ret = -EINVAL;
>> +		goto out_unlock;
>> +	}
>> +
>> +	ret = resctrl_process_configs(buf, &evt_cfg);
>> +	if (!ret && mevt->evt_cfg != evt_cfg) {
>> +		mevt->evt_cfg = evt_cfg;
>> +		resctrl_update_cntr_allrdtgrp(mevt);
>> +	}
>> +
>> +out_unlock:
>> +	mutex_unlock(&rdtgroup_mutex);
>> +	cpus_read_unlock();
>> +
>> +	return ret ?: nbytes;
>> +}
>> +
>>   /* rdtgroup information files for one cache resource. */
>>   static struct rftype res_common_files[] = {
>>   	{
>> @@ -2042,9 +2113,10 @@ static struct rftype res_common_files[] = {
>>   	},
>>   	{
>>   		.name		= "event_filter",
>> -		.mode		= 0444,
>> +		.mode		= 0644,
>>   		.kf_ops		= &rdtgroup_kf_single_ops,
>>   		.seq_show	= event_filter_show,
>> +		.write		= event_filter_write,
>>   	},
>>   	{
>>   		.name		= "mbm_assign_mode",
> 
> Reinette
> 

thanks
Babu