linux-kernel - Re: [PATCH v16 13/34] fs/resctrl: Introduce interface to display number of free MBM counters

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Message-ID: <f07836ca-8504-4619-861d-c2e9a6f517c0@intel.com>
Date: Wed, 6 Aug 2025 14:31:09 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: <babu.moger@....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>,
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	<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 13/34] fs/resctrl: Introduce interface to display
 number of free MBM counters

Hi Babu,

On 8/6/25 2:19 PM, Moger, Babu wrote:
>> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
>> index a09566720d4f..15d10c346307 100644
>> --- a/fs/resctrl/rdtgroup.c
>> +++ b/fs/resctrl/rdtgroup.c
>> @@ -1853,6 +1853,48 @@ static int resctrl_num_mbm_cntrs_show(struct kernfs_open_file *of,
>>  	return 0;
>>  }
>>  
>> +static int resctrl_available_mbm_cntrs_show(struct kernfs_open_file *of,
>> +					    struct seq_file *s, void *v)
>> +{
>> +	struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
>> +	struct rdt_mon_domain *dom;
>> +	bool sep = false;
>> +	u32 cntrs, i;
>> +	int ret = 0;
>> +
>> +	cpus_read_lock();
>> +	mutex_lock(&rdtgroup_mutex);
>> +
>> +	rdt_last_cmd_clear();
>> +
>> +	if (!resctrl_arch_mbm_cntr_assign_enabled(r)) {
>> +		rdt_last_cmd_puts("mbm_event mode is not enabled\n");
>> +		ret = -EINVAL;
>> +		goto out_unlock;
>> +	}
>> +
>> +	list_for_each_entry(dom, &r->mon_domains, hdr.list) {
>> +		if (sep)
>> +			seq_putc(s, ';');
>> +
>> +		cntrs = 0;
>> +		for (i = 0; i < r->mon.num_mbm_cntrs; i++) {
>> +			if (!dom->cntr_cfg[i].rdtgrp)
>> +				cntrs++;
>> +		}
>> +
>> +		seq_printf(s, "%d=%u", dom->hdr.id, cntrs);
>> +		sep = true;
>> +	}
>> +	seq_putc(s, '\n');
>> +
>> +out_unlock:
>> +	mutex_unlock(&rdtgroup_mutex);
>> +	cpus_read_unlock();
>> +
>> +	return ret;
>> +}
>> +
> 
> This also can be moved to monitor.c.  What do you think?

Yes, I believe monitor.c is most appropriate for all the monitoring
related handlers [1].

Reinette

[1] https://lore.kernel.org/lkml/0fa9a12b-e900-4ceb-b59c-e653ec3db0ca@intel.com/