linux-kernel - Re: [RFC PATCH v3 09/17] x86/resctrl: Introduce assign state for the mon group

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Date: Tue, 16 Apr 2024 14:52:55 -0500
From: "Moger, Babu" <babu.moger@....com>
To: Peter Newman <peternewman@...gle.com>
Cc: corbet@....net, fenghua.yu@...el.com, reinette.chatre@...el.com,
 tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
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 james.morse@....com
Subject: Re: [RFC PATCH v3 09/17] x86/resctrl: Introduce assign state for the
 mon group

Hi Peter,

On 4/16/24 13:52, Peter Newman wrote:
> Hi Babu,
> 
> On Thu, Mar 28, 2024 at 6:08 PM Babu Moger <babu.moger@....com> wrote:
>>
>> +/*
>> + * monitor group's state when ABMC is supported
>> + */
>> +#define ASSIGN_NONE                    0
>> +#define ASSIGN_TOTAL                   BIT(0)
>> +#define ASSIGN_LOCAL                   BIT(1)
> 
> We already have an enumeration for the monitoring events (i.e.,
> QOS_L3_MBM_TOTAL_EVENT_ID), which should already be suitable for
> maintaining a bitmap of which events have assigned monitors.
> 

/*
 * Event IDs, the values match those used to program IA32_QM_EVTSEL before
 * reading IA32_QM_CTR on RDT systems.
 */
enum resctrl_event_id {
        QOS_L3_OCCUP_EVENT_ID           = 0x01,
        QOS_L3_MBM_TOTAL_EVENT_ID       = 0x02,
        QOS_L3_MBM_LOCAL_EVENT_ID       = 0x03,
};

I think you are referring to this definition. We need just one bit for
each event. The QOS_L3_MBM_LOCAL_EVENT_ID definition(both bit 0 and bit 1
set here) does not work for us here.

I can change the definition to something like this.

+#define ASSIGN_NONE                    0
+#define ASSIGN_TOTAL                   BIT(QOS_L3_MBM_TOTAL_EVENT_ID)
+#define ASSIGN_LOCAL                   BIT(QOS_L3_MBM_LOCAL_EVENT_ID)

Is that what you meant?

-- 
Thanks
Babu Moger