Hi Babu,
On 5/15/25 3:51 PM, Babu Moger wrote:
> The mbm_cntr_assign mode offers "num_mbm_cntrs" number of counters that
> can be assigned to an RMID, event pair and monitor the bandwidth as long
> as it is assigned. If all the counters are in use, the kernel will log the
> error message "Unable to allocate counter in domain" 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.
>
> Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
> ---
...
> ---
> fs/resctrl/internal.h | 2 ++
> fs/resctrl/monitor.c | 60 +++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 62 insertions(+)
>
> diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
> index ce4fcac91937..64ddc107fcab 100644
> --- a/fs/resctrl/internal.h
> +++ b/fs/resctrl/internal.h
> @@ -379,6 +379,8 @@ int resctrl_find_cleanest_closid(void);
>
> int resctrl_assign_cntr_event(struct rdt_resource *r, struct rdt_mon_domain *d,
> struct rdtgroup *rdtgrp, enum resctrl_event_id evtid);
> +int resctrl_unassign_cntr_event(struct rdt_resource *r, struct rdt_mon_domain *d,
> + struct rdtgroup *rdtgrp, enum resctrl_event_id evtid);
>
> #ifdef CONFIG_RESCTRL_FS_PSEUDO_LOCK
> int rdtgroup_locksetup_enter(struct rdtgroup *rdtgrp);
> diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
> index d76fd0840946..fbc938bd3b23 100644
> --- a/fs/resctrl/monitor.c
> +++ b/fs/resctrl/monitor.c
> @@ -989,6 +989,14 @@ static int mbm_cntr_alloc(struct rdt_resource *r, struct rdt_mon_domain *d,
> return -ENOSPC;
> }
>
> +/*
> + * mbm_cntr_free() - Reset cntr_id to zero.
"Reset cntr_id to zero"? cntr_id is an index to an array.
Please provide accurate and useful descriptions.
> + */
> +static void mbm_cntr_free(struct rdt_mon_domain *d, int cntr_id)
> +{
> + memset(&d->cntr_cfg[cntr_id], 0, sizeof(struct mbm_cntr_cfg));
> +}
> +
> /*
> * mbm_get_mon_event() - Return the mon_evt entry for the matching evtid.
> */
> @@ -1068,3 +1076,55 @@ int resctrl_assign_cntr_event(struct rdt_resource *r, struct rdt_mon_domain *d,
>
> return ret;
> }
> +
> +/*
> + * Unassign and free the counter if assigned.
> + */
> +static int resctrl_free_config_cntr(struct rdt_resource *r, struct rdt_mon_domain *d,
> + struct rdtgroup *rdtgrp, enum resctrl_event_id evtid)
> +{
> + struct mon_evt *mevt;
> + int cntr_id;
> +
> + cntr_id = mbm_cntr_get(r, d, rdtgrp, evtid);
> +
> + /* If there is no cntr_id assigned, nothing to do */
> + if (cntr_id < 0)
> + return 0;
> +
> + mevt = mbm_get_mon_event(r, evtid);
> + if (!mevt) {
> + rdt_last_cmd_printf("Invalid event id %d\n", evtid);
Similar to previous comment this is in kernel bug territory and could be simplified
by passing mon_evt instead. Although this is the unassign portion where
evt_cfg seems unnecessary.
> + return -EINVAL;
> + }
> +
> + resctrl_config_cntr(r, d, evtid, rdtgrp->mon.rmid, rdtgrp->closid,
> + cntr_id, mevt->evt_cfg, false);
> +
> + mbm_cntr_free(d, cntr_id);
> +
> + return 0;
> +}
> +
> +/*
> + * Unassign a hardware counter associated with @evtid from the domain and
> + * the group. Unassign the counters from all the domains if @d is NULL else
> + * unassign from @d.
> + */
> +int resctrl_unassign_cntr_event(struct rdt_resource *r, struct rdt_mon_domain *d,
> + struct rdtgroup *rdtgrp, enum resctrl_event_id evtid)
> +{
> + int ret;
> +
> + if (!d) {
> + list_for_each_entry(d, &r->mon_domains, hdr.list) {
> + ret = resctrl_free_config_cntr(r, d, rdtgrp, evtid);
> + if (ret)
> + return ret;
> + }
> + } else {
> + ret = resctrl_free_config_cntr(r, d, rdtgrp, evtid);
> + }
> +
> + return ret;
> +}
Reinette
