linux-kernel - Re: [PATCH v16 32/34] fs/resctrl: Introduce the interface to switch between monitor modes

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Message-ID: <f2feaa83-b765-4ba0-a85c-df60e2a96aac@amd.com>
Date: Tue, 12 Aug 2025 14:18:48 -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 32/34] fs/resctrl: Introduce the interface to switch
 between monitor modes

Hi Reinette,

On 7/30/25 15:11, Reinette Chatre wrote:
> Hi Babu,
> 
> On 7/25/25 11:29 AM, Babu Moger wrote:
>> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
>> index 1aeac350774d..68ba08e95a54 100644
>> --- a/fs/resctrl/rdtgroup.c
>> +++ b/fs/resctrl/rdtgroup.c
>> @@ -1865,6 +1865,75 @@ static int resctrl_mbm_assign_mode_show(struct kernfs_open_file *of,
>>  	return 0;
>>  }
>>  
>> +static ssize_t resctrl_mbm_assign_mode_write(struct kernfs_open_file *of,
>> +					     char *buf, size_t nbytes, loff_t off)
> 
> Please move to monitor.c
> 

Sure.

>> +{
>> +	struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
>> +	struct rdt_mon_domain *d;
>> +	int ret = 0;
>> +	bool enable;
>> +
>> +	/* 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();
>> +
>> +	if (!strcmp(buf, "default")) {
>> +		enable = 0;
>> +	} else if (!strcmp(buf, "mbm_event")) {
>> +		if (r->mon.mbm_cntr_assignable) {
>> +			enable = 1;
>> +		} else {
>> +			ret = -EINVAL;
>> +			rdt_last_cmd_puts("mbm_event mode is not supported\n");
>> +			goto out_unlock;
>> +		}
>> +	} else {
>> +		ret = -EINVAL;
>> +		rdt_last_cmd_puts("Unsupported assign mode\n");
>> +		goto out_unlock;
>> +	}
>> +
>> +	if (enable != resctrl_arch_mbm_cntr_assign_enabled(r)) {
>> +		ret = resctrl_arch_mbm_cntr_assign_set(r, enable);
>> +		if (ret)
>> +			goto out_unlock;
>> +
>> +		/* Update the visibility of BMEC related files */
>> +		resctrl_bmec_files_show(r, NULL, !enable);
>> +
>> +		/*
>> +		 * Initialize the default memory transaction values for
>> +		 * total and local events.
>> +		 */
>> +		if (resctrl_is_mon_event_enabled(QOS_L3_MBM_TOTAL_EVENT_ID))
>> +			mon_event_all[QOS_L3_MBM_TOTAL_EVENT_ID].evt_cfg = MAX_EVT_CONFIG_BITS;
>> +		if (resctrl_is_mon_event_enabled(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;
> 
> This needs to take into account the configurations that
> hardware supports.
> 

Yes. Sure.

-- 
Thanks
Babu Moger