Message-ID: <69d7f38c-2df4-4191-80cc-cc5c724b2050@intel.com>
Date: Thu, 19 Dec 2024 15:22:25 -0800
From: Reinette Chatre <reinette.chatre@...el.com>
To: Babu Moger <babu.moger@....com>, <corbet@....net>, <tglx@...utronix.de>,
	<mingo@...hat.com>, <bp@...en8.de>, <dave.hansen@...ux.intel.com>,
	<tony.luck@...el.com>, <peternewman@...gle.com>
CC: <fenghua.yu@...el.com>, <x86@...nel.org>, <hpa@...or.com>,
	<paulmck@...nel.org>, <akpm@...ux-foundation.org>, <thuth@...hat.com>,
	<rostedt@...dmis.org>, <xiongwei.song@...driver.com>,
	<pawan.kumar.gupta@...ux.intel.com>, <daniel.sneddon@...ux.intel.com>,
	<jpoimboe@...nel.org>, <perry.yuan@....com>, <sandipan.das@....com>,
	<kai.huang@...el.com>, <xiaoyao.li@...el.com>, <seanjc@...gle.com>,
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	<mario.limonciello@....com>, <james.morse@....com>,
	<tan.shaopeng@...itsu.com>, <linux-doc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <maciej.wieczor-retman@...el.com>,
	<eranian@...gle.com>
Subject: Re: [PATCH v10 16/24] x86/resctrl: Add interface to the assign
 counter

Hi Babu,

On 12/12/24 12:15 PM, Babu Moger wrote:
> The mbm_cntr_assign mode offers several counters that can be assigned
> to an RMID, event pair and monitor the bandwidth as long as it is
> assigned.
> 
> Counters are managed at the domain level. Introduce the interface to
> allocate/free/assign the counters.

Changelog of previous patch also claimed to "Provide the interface to assign the
counter ids to RMID." Please let changelogs describe the change more accurately.

(This still does not provide a user interface so what is meant by interface is
unclear)


> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 849bcfe4ea5b..70d2577fc377 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -704,5 +704,8 @@ unsigned int mon_event_config_index_get(u32 evtid);
>  int resctrl_arch_config_cntr(struct rdt_resource *r, struct rdt_mon_domain *d,
>  			     enum resctrl_event_id evtid, u32 rmid, u32 closid,
>  			     u32 cntr_id, bool assign);
> -
> +int rdtgroup_assign_cntr_event(struct rdt_resource *r, struct rdtgroup *rdtgrp,
> +			       struct rdt_mon_domain *d, enum resctrl_event_id evtid);

Could you please be consistent in the ordering of parameters?

int rdtgroup_assign_cntr_event(struct rdt_resource *r, struct rdt_mon_domain *d, 
			       struct rdtgroup *rdtgrp, enum resctrl_event_id evtid);

> +struct mbm_state *get_mbm_state(struct rdt_mon_domain *d, u32 closid,
> +				u32 rmid, enum resctrl_event_id evtid);
>  #endif /* _ASM_X86_RESCTRL_INTERNAL_H */
> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
> index f857af361af1..8823cd97ff1f 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -575,8 +575,8 @@ void free_rmid(u32 closid, u32 rmid)
>  		list_add_tail(&entry->list, &rmid_free_lru);
>  }
>  
> -static struct mbm_state *get_mbm_state(struct rdt_mon_domain *d, u32 closid,
> -				       u32 rmid, enum resctrl_event_id evtid)
> +struct mbm_state *get_mbm_state(struct rdt_mon_domain *d, u32 closid,
> +				u32 rmid, enum resctrl_event_id evtid)
>  {
>  	u32 idx = resctrl_arch_rmid_idx_encode(closid, rmid);
>  
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index e895d2415f22..1c8694a68cf4 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -1927,6 +1927,116 @@ int resctrl_arch_config_cntr(struct rdt_resource *r, struct rdt_mon_domain *d,
>  	return 0;
>  }
>  
> +/*
> + * Configure the counter for the event, RMID pair for the domain.

This description can be more helpful ... it essentially just re-writes function
header.

> + */
> +static int resctrl_config_cntr(struct rdt_resource *r, struct rdt_mon_domain *d,
> +			       enum resctrl_event_id evtid, u32 rmid, u32 closid,
> +			       u32 cntr_id, bool assign)
> +{
> +	struct mbm_state *m;
> +	int ret;
> +
> +	ret = resctrl_arch_config_cntr(r, d, evtid, rmid, closid, cntr_id, assign);
> +	if (ret)
> +		return ret;
> +
> +	m = get_mbm_state(d, closid, rmid, evtid);
> +	if (m)
> +		memset(m, 0, sizeof(struct mbm_state));
> +
> +	return ret;
> +}
> +
> +static bool mbm_cntr_assigned(struct rdt_resource *r, struct rdt_mon_domain *d,
> +			      struct rdtgroup *rdtgrp, enum resctrl_event_id evtid)
> +{
> +	int cntr_id;
> +
> +	for (cntr_id = 0; cntr_id < r->mon.num_mbm_cntrs; cntr_id++) {
> +		if (d->cntr_cfg[cntr_id].rdtgrp == rdtgrp &&
> +		    d->cntr_cfg[cntr_id].evtid == evtid)
> +			return true;
> +	}
> +
> +	return false;
> +}
> +
> +static int mbm_cntr_alloc(struct rdt_resource *r, struct rdt_mon_domain *d,
> +			  struct rdtgroup *rdtgrp, enum resctrl_event_id evtid)
> +{
> +	int cntr_id;
> +
> +	for (cntr_id = 0; cntr_id < r->mon.num_mbm_cntrs; cntr_id++) {
> +		if (!d->cntr_cfg[cntr_id].rdtgrp) {
> +			d->cntr_cfg[cntr_id].rdtgrp = rdtgrp;
> +			d->cntr_cfg[cntr_id].evtid = evtid;
> +			return cntr_id;
> +		}
> +	}
> +
> +	return -EINVAL;

This can be -ENOSPC

> +}
> +
> +static void mbm_cntr_free(struct rdt_resource *r, struct rdt_mon_domain *d,
> +			  struct rdtgroup *rdtgrp, enum resctrl_event_id evtid)
> +{
> +	int cntr_id;
> +
> +	for (cntr_id = 0; cntr_id < r->mon.num_mbm_cntrs; cntr_id++) {
> +		if (d->cntr_cfg[cntr_id].rdtgrp == rdtgrp &&
> +		    d->cntr_cfg[cntr_id].evtid == evtid)
> +			memset(&d->cntr_cfg[cntr_id], 0, sizeof(struct mbm_cntr_cfg));
> +	}
> +}

>From what I can tell the counter ID is always available when the counter is freed so
it can just be freed directly without looping over array?

> +
> +/*
> + * Assign a hardware counter to event @evtid of group @rdtgrp.
> + * Counter will be assigned to all the domains if rdt_mon_domain is NULL

(to be consistent) "if rdt_mon_domain is NULL" -> "if @d is NULL"

> + * else the counter will be assigned to specific domain.

"will be assigned to specific domain" -> "will be assigned to @d"

Reinette

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