linux-kernel - Re: [PATCH v3 2/8] x86/resctrl: Remove hard code of RDT_RESOURCE

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Message-ID: <7f56cc04-021e-ff75-255a-dbfd80a3f6d7@intel.com>
Date:   Tue, 18 Jul 2023 13:37:24 -0700
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     Tony Luck <tony.luck@...el.com>, Fenghua Yu <fenghua.yu@...el.com>,
        "Peter Newman" <peternewman@...gle.com>,
        Jonathan Corbet <corbet@....net>,
        "Shuah Khan" <skhan@...uxfoundation.org>, <x86@...nel.org>
CC:     Shaopeng Tan <tan.shaopeng@...itsu.com>,
        James Morse <james.morse@....com>,
        Jamie Iles <quic_jiles@...cinc.com>,
        Babu Moger <babu.moger@....com>,
        Randy Dunlap <rdunlap@...radead.org>,
        <linux-kernel@...r.kernel.org>, <linux-doc@...r.kernel.org>,
        <patches@...ts.linux.dev>
Subject: Re: [PATCH v3 2/8] x86/resctrl: Remove hard code of RDT_RESOURCE_L3
 in monitor.c

Hi Tony,

Regarding subject and change: Why is the focus on just monitor.c?
Hardcoding of RDT_RESOURCE_L3 as monitoring resource is done
elsewhere also (rdtgroup.c:rdt_get_tree()) - why not treat all
hardcoding?

On 7/13/2023 9:32 AM, Tony Luck wrote:

...

> @@ -759,9 +761,9 @@ static struct mon_evt mbm_local_event = {
>  /*
>   * Initialize the event list for the resource.
>   *
> - * Note that MBM events are also part of RDT_RESOURCE_L3 resource
> - * because as per the SDM the total and local memory bandwidth
> - * are enumerated as part of L3 monitoring.
> + * Monitor events can either be part of RDT_RESOURCE_L3 resource,
> + * or they may be per NUMA node on systems with sub-NUMA cluster
> + * enabled and are then in the RDT_RESOURCE_NODE resource.
>   */
>  static void l3_mon_evt_init(struct rdt_resource *r)
>  {
> @@ -773,6 +775,8 @@ static void l3_mon_evt_init(struct rdt_resource *r)
>  		list_add_tail(&mbm_total_event.list, &r->evt_list);
>  	if (is_mbm_local_enabled())
>  		list_add_tail(&mbm_local_event.list, &r->evt_list);
> +
> +	mon_resource = r;
>  }
>  

This does not seem like the right place for this initialization.
mon_evt_init() has a single job that the function comment clearly
states: "Initialize the event list for the resource". What does
the global mon_resource have to do with the event list?

Would get_rdt_mon_resources() not be more appropriate?

Although, looking ahead it is not clear to me why this is needed.
I'll try to focus my responses to the individual patches in this
regard.

>  int __init rdt_get_mon_l3_config(struct rdt_resource *r)

Reinette