linux-kernel - Re: [PATCH v16 29/34] fs/resctrl: Introduce mbm_L3_assignments to list assignments in a group

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Message-ID: <a98edca8-9f14-4f90-9e49-01d07fea2d58@amd.com>
Date: Mon, 11 Aug 2025 18:42:37 -0500
From: "Moger, Babu" <babu.moger@....com>
To: Reinette Chatre <reinette.chatre@...el.com>, corbet@....net,
 tony.luck@...el.com, james.morse@....com, tglx@...utronix.de,
 mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com
Cc: Dave.Martin@....com, x86@...nel.org, hpa@...or.com,
 akpm@...ux-foundation.org, paulmck@...nel.org, rostedt@...dmis.org,
 Neeraj.Upadhyay@....com, david@...hat.com, arnd@...db.de, fvdl@...gle.com,
 seanjc@...gle.com, jpoimboe@...nel.org, pawan.kumar.gupta@...ux.intel.com,
 xin@...or.com, manali.shukla@....com, tao1.su@...ux.intel.com,
 sohil.mehta@...el.com, kai.huang@...el.com, xiaoyao.li@...el.com,
 peterz@...radead.org, xin3.li@...el.com, kan.liang@...ux.intel.com,
 mario.limonciello@....com, thomas.lendacky@....com, perry.yuan@....com,
 gautham.shenoy@....com, chang.seok.bae@...el.com, linux-doc@...r.kernel.org,
 linux-kernel@...r.kernel.org, peternewman@...gle.com, eranian@...gle.com
Subject: Re: [PATCH v16 29/34] fs/resctrl: Introduce mbm_L3_assignments to
 list assignments in a group

Hi Reinette,

On 7/30/2025 3:09 PM, Reinette Chatre wrote:
> Hi Babu,
>
> On 7/25/25 11:29 AM, Babu Moger wrote:
>> Introduce the mbm_L3_assignments resctrl file associated with CTRL_MON and
>> MON resource groups to display the counter assignment states of the
>> resource group when "mbm_event" counter assignment mode is enabled.
>>
>> The list is displayed in the following format:
> needs imperative:
>   "Display the list ..."
Sure.
>
>> <Event>:<Domain id>=<Assignment state>;<Domain id>=<Assignment state>
>>
>> Event: A valid MBM event listed in
>>         /sys/fs/resctrl/info/L3_MON/event_configs directory.
>>
>> Domain ID: A valid domain ID.
>>
>> The assignment state can be one of the following:
>>
>> _ : No counter assigned.
>>
>> e : Counter assigned exclusively.
>>
>> Example:
>> To list the assignment states for the default group
>> $ cd /sys/fs/resctrl
>> $ cat /sys/fs/resctrl/mbm_L3_assignments
>> mbm_total_bytes:0=e;1=e
>> mbm_local_bytes:0=e;1=e
>>
>> Signed-off-by: Babu Moger <babu.moger@....com>
>> ---
> ...
>
>
>> diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
>> index 5cf1b79c17f5..ebc049105949 100644
>> --- a/fs/resctrl/monitor.c
>> +++ b/fs/resctrl/monitor.c
>> @@ -1080,6 +1080,7 @@ int resctrl_mon_resource_init(void)
>>   		resctrl_file_fflags_init("event_filter", RFTYPE_ASSIGN_CONFIG);
>>   		resctrl_file_fflags_init("mbm_assign_on_mkdir", RFTYPE_MON_INFO |
>>   					 RFTYPE_RES_CACHE);
>> +		resctrl_file_fflags_init("mbm_L3_assignments", RFTYPE_MON_BASE);
>>   	}
>>   
>>   	return 0;
>> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
>> index d087ba990cd3..47716e623a9c 100644
>> --- a/fs/resctrl/rdtgroup.c
>> +++ b/fs/resctrl/rdtgroup.c
>> @@ -1931,6 +1931,54 @@ static ssize_t resctrl_mbm_assign_on_mkdir_write(struct kernfs_open_file *of,
>>   	return nbytes;
>>   }
>>   
>> +static int mbm_L3_assignments_show(struct kernfs_open_file *of, struct seq_file *s, void *v)
> Please move to monitor.c (then mbm_cntr_get() can be private to monitor.c also).


Sure.

>
>> +{
>> +	struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
>> +	struct rdt_mon_domain *d;
>> +	struct rdtgroup *rdtgrp;
>> +	struct mon_evt *mevt;
>> +	int ret = 0;
>> +	bool sep;
>> +
>> +	rdtgrp = rdtgroup_kn_lock_live(of->kn);
>> +	if (!rdtgrp) {
>> +		ret = -ENOENT;
>> +		goto out_unlock;
>> +	}
>> +
>> +	rdt_last_cmd_clear();
>> +	if (!resctrl_arch_mbm_cntr_assign_enabled(r)) {
>> +		rdt_last_cmd_puts("mbm_event mode is not enabled\n");
>> +		ret = -ENOENT;
> The error returned by the files when "mbm_event" is disabled (but supported) is
> inconsistent. All but this one return EINVAL. Please make return code consistent.


Yes. Sure.

>
>> +		goto out_unlock;
>> +	}
>> +
>> +	for_each_mon_event(mevt) {
>> +		if (mevt->rid != r->rid || !mevt->enabled || !resctrl_is_mbm_event(mevt->evtid))
>> +			continue;
>> +
>> +		sep = false;
>> +		seq_printf(s, "%s:", mevt->name);
>> +		list_for_each_entry(d, &r->mon_domains, hdr.list) {
>> +			if (sep)
>> +				seq_putc(s, ';');
>> +
>> +			if (mbm_cntr_get(r, d, rdtgrp, mevt->evtid) < 0)
>> +				seq_printf(s, "%d=_", d->hdr.id);
>> +			else
>> +				seq_printf(s, "%d=e", d->hdr.id);
>> +
>> +			sep = true;
>> +		}
>> +		seq_putc(s, '\n');
>> +	}
>> +
>> +out_unlock:
>> +	rdtgroup_kn_unlock(of->kn);
>> +
>> +	return ret;
>> +}
>> +
>>   /* rdtgroup information files for one cache resource. */
>>   static struct rftype res_common_files[] = {
>>   	{
> Reinette
>