linux-kernel - Re: [PATCH v9 3/9] x86/resctrl: Modify update_mba_bw() to use per ctrl

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Message-ID: <b4b31f4f-7f09-4ee3-9373-6ffe5ea859a6@amd.com>
Date: Fri, 15 Nov 2024 10:21:01 -0600
From: "Moger, Babu" <bmoger@....com>
To: Tony Luck <tony.luck@...el.com>, Fenghua Yu <fenghua.yu@...el.com>,
 Reinette Chatre <reinette.chatre@...el.com>,
 Peter Newman <peternewman@...gle.com>, Jonathan Corbet <corbet@....net>,
 x86@...nel.org
Cc: James Morse <james.morse@....com>, Jamie Iles <quic_jiles@...cinc.com>,
 Babu Moger <babu.moger@....com>, Randy Dunlap <rdunlap@...radead.org>,
 "Shaopeng Tan (Fujitsu)" <tan.shaopeng@...itsu.com>,
 linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
 patches@...ts.linux.dev
Subject: Re: [PATCH v9 3/9] x86/resctrl: Modify update_mba_bw() to use per
 ctrl_mon group event

Hi Tony,

On 11/13/2024 6:17 PM, Tony Luck wrote:
> Instead of hard-coding the memory bandwidth local event as the
> input to the mba_sc feedback look, use the event that the user
> configured for each ctrl_mon group.
> 
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---
>   arch/x86/kernel/cpu/resctrl/monitor.c | 23 ++++++++++++++++++-----
>   1 file changed, 18 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
> index 7ef1a293cc13..2176e355e864 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -752,20 +752,31 @@ static void update_mba_bw(struct rdtgroup *rgrp, struct rdt_mon_domain *dom_mbm)
>   	u32 closid, rmid, cur_msr_val, new_msr_val;
>   	struct mbm_state *pmbm_data, *cmbm_data;
>   	struct rdt_ctrl_domain *dom_mba;
> +	enum resctrl_event_id evt_id;
>   	struct rdt_resource *r_mba;
> -	u32 cur_bw, user_bw, idx;
>   	struct list_head *head;
>   	struct rdtgroup *entry;
> +	u32 cur_bw, user_bw;
>   
> -	if (!is_mbm_local_enabled())
> +	if (!is_mbm_enabled())
>   		return;
>   
>   	r_mba = &rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl;
> +	evt_id = rgrp->mba_mbps_event;
> +
> +	if (WARN_ON_ONCE(!is_mbm_event(evt_id)))
> +		return;

I feel this check is enough.

> +	if (WARN_ON_ONCE(evt_id == QOS_L3_MBM_LOCAL_EVENT_ID && !is_mbm_local_enabled()))
> +		return;
> +	if (WARN_ON_ONCE(evt_id == QOS_L3_MBM_TOTAL_EVENT_ID && !is_mbm_total_enabled()))
> +		return;

These two checks are not necessary.  You are already validating it while 
initializing(in patch 7).

> +
>   
>   	closid = rgrp->closid;
>   	rmid = rgrp->mon.rmid;
> -	idx = resctrl_arch_rmid_idx_encode(closid, rmid);
> -	pmbm_data = &dom_mbm->mbm_local[idx];
> +	pmbm_data = get_mbm_state(dom_mbm, closid, rmid, evt_id);
> +	if (WARN_ON_ONCE(!pmbm_data))
> +		return;
>   
>   	dom_mba = get_ctrl_domain_from_cpu(smp_processor_id(), r_mba);
>   	if (!dom_mba) {
> @@ -784,7 +795,9 @@ static void update_mba_bw(struct rdtgroup *rgrp, struct rdt_mon_domain *dom_mbm)
>   	 */
>   	head = &rgrp->mon.crdtgrp_list;
>   	list_for_each_entry(entry, head, mon.crdtgrp_list) {
> -		cmbm_data = &dom_mbm->mbm_local[entry->mon.rmid];
> +		cmbm_data = get_mbm_state(dom_mbm, entry->closid, entry->mon.rmid, evt_id);
> +		if (WARN_ON_ONCE(!cmbm_data))
> +			return;
>   		cur_bw += cmbm_data->prev_bw;
>   	}
>   

-- 
- Babu Moger