Re: [PATCH v16 17/34] fs/resctrl: Add the functionality to assign MBM events

[Reinette Chatre]

Hi Babu,

On 7/25/25 11:29 AM, Babu Moger wrote:
> When supported, "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.
> 
> Add the functionality to allocate and assign a counter to an RMID, event
> pair in the domain.
> 
> If all the counters are in use, kernel will log the error message

I think dropping "kernel will" will help the text to be imperative.

> "Failed to allocate counter for <event> in domain <id>" in
> /sys/fs/resctrl/info/last_cmd_status when a new assignment is requested.

"when a new assignment is requested" can be dropped. Or alternatively:
	Log the error message "Failed to allocate counter for <event> in domain
	<id>" in /sys/fs/resctrl/info/last_cmd_status if all the counters
	are in use.

> Exit on the first failure when assigning counters across all the domains.
> 
> Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
> ---

...

> ---
>  fs/resctrl/internal.h |   3 +
>  fs/resctrl/monitor.c  | 130 ++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 133 insertions(+)
> 
> diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
> index db3a0f12ad77..419423bdabdc 100644
> --- a/fs/resctrl/internal.h
> +++ b/fs/resctrl/internal.h
> @@ -387,6 +387,9 @@ bool closid_allocated(unsigned int closid);
>  
>  int resctrl_find_cleanest_closid(void);
>  
> +int rdtgroup_assign_cntr_event(struct rdt_mon_domain *d, struct rdtgroup *rdtgrp,
> +			       struct mon_evt *mevt);
> +

This internal.h change does not look necessary? Looking ahead this is because 
rdtgroup.c:rdtgroup_assign_cntrs() needs it, but rdtgroup_assign_cntrs()
also belongs in monitor.c, no? 

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

...

> +/*
> + * rdtgroup_alloc_assign_cntr() - Allocate a counter ID and assign it to the event
> + * pointed to by @mevt and the resctrl group @rdtgrp within the domain @d.
> + *
> + * Return:
> + * 0 on success, < 0 on failure.
> + */
> +static int rdtgroup_alloc_assign_cntr(struct rdt_resource *r, struct rdt_mon_domain *d,
> +				      struct rdtgroup *rdtgrp, struct mon_evt *mevt)
> +{
> +	int cntr_id;
> +
> +	/* No action required if the counter is assigned already. */
> +	cntr_id = mbm_cntr_get(r, d, rdtgrp, mevt->evtid);
> +	if (cntr_id >= 0)
> +		return 0;
> +
> +	cntr_id = mbm_cntr_alloc(r, d, rdtgrp, mevt->evtid);
> +	if (cntr_id <  0) {

Extra space above.

> +		rdt_last_cmd_printf("Failed to allocate counter for %s in domain %d\n",
> +				    mevt->name, d->hdr.id);
> +		return cntr_id;
> +	}
> +
> +	rdtgroup_assign_cntr(r, d, mevt->evtid, rdtgrp->mon.rmid, rdtgrp->closid, cntr_id, true);
> +
> +	return 0;
> +}
> +

Reinette