linux-kernel - Re: [PATCH v17 18/33] fs/resctrl: Add the functionality to unassign MBM events

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Message-ID: <e3f49b51-b03c-4e6f-92b0-fbf7668c754d@intel.com>
Date: Tue, 2 Sep 2025 19:33:02 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Babu Moger <babu.moger@....com>, <corbet@....net>, <tony.luck@...el.com>,
	<tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>
CC: <Dave.Martin@....com>, <james.morse@....com>, <x86@...nel.org>,
	<hpa@...or.com>, <akpm@...ux-foundation.org>, <rostedt@...dmis.org>,
	<paulmck@...nel.org>, <pawan.kumar.gupta@...ux.intel.com>, <kees@...nel.org>,
	<arnd@...db.de>, <fvdl@...gle.com>, <seanjc@...gle.com>,
	<thomas.lendacky@....com>, <yosry.ahmed@...ux.dev>, <xin@...or.com>,
	<sohil.mehta@...el.com>, <kai.huang@...el.com>, <xiaoyao.li@...el.com>,
	<peterz@...radead.org>, <mario.limonciello@....com>, <xin3.li@...el.com>,
	<perry.yuan@....com>, <chang.seok.bae@...el.com>,
	<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<peternewman@...gle.com>, <eranian@...gle.com>, <gautham.shenoy@....com>
Subject: Re: [PATCH v17 18/33] fs/resctrl: Add the functionality to unassign
 MBM events

Hi Babu,

On 8/14/25 7:25 PM, Babu Moger wrote:
> The "mbm_event" counter assignment mode offers "num_mbm_cntrs" number of
> counters that can be assigned to RMID, event pairs and monitor bandwidth
> usage as long as it is assigned. If all the counters are in use, the kernel
> logs the error message "Failed to allocate counter for <event> in domain
> <id>" in /sys/fs/resctrl/info/last_cmd_status when a new assignment is
> requested.
> 
> To make space for a new assignment, users must unassign an already
> assigned counter and retry the assignment again.
> 
> Add the functionality to unassign and free the counters in the domain.
> Also, add the helper rdtgroup_unassign_cntrs() to unassign counters in the
> group.
> 
> Signed-off-by: Babu Moger <babu.moger@....com>
> ---

Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>

Reinette