linux-kernel - Re: [PATCH v16 18/34] fs/resctrl: Add the functionality to unassign MBM events

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Message-ID: <a65263be-523f-48a7-9473-4f4db1b458f7@intel.com>
Date: Wed, 30 Jul 2025 12:53:43 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Babu Moger <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>,
	<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 18/34] fs/resctrl: Add the functionality to unassign
 MBM events

Hi Babu,

On 7/25/25 11:29 AM, 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 "Unable to allocate counter in domain" in

Needs an update to match new message.

> /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.
> 
> Signed-off-by: Babu Moger <babu.moger@....com>
> ---


...


> ---
>  fs/resctrl/internal.h |  2 ++
>  fs/resctrl/monitor.c  | 46 +++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 48 insertions(+)
> 
> diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
> index 419423bdabdc..216588842444 100644
> --- a/fs/resctrl/internal.h
> +++ b/fs/resctrl/internal.h
> @@ -389,6 +389,8 @@ int resctrl_find_cleanest_closid(void);
>  
>  int rdtgroup_assign_cntr_event(struct rdt_mon_domain *d, struct rdtgroup *rdtgrp,
>  			       struct mon_evt *mevt);
> +void rdtgroup_unassign_cntr_event(struct rdt_mon_domain *d, struct rdtgroup *rdtgrp,
> +				  struct mon_evt *mevt);
>  

Similar comment as previous patch. Please try to keep all monitoring code in
monitor.c. The caller rdtgroup_unassign_cntrs() can move to monitor.c and it
can instead be made available via internal.h


>  #ifdef CONFIG_RESCTRL_FS_PSEUDO_LOCK
>  int rdtgroup_locksetup_enter(struct rdtgroup *rdtgrp);

Reinette