linux-kernel - Re: [PATCH v9 19/26] x86/resctrl: Add the interface to unassign a MBM counter

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Message-ID: <CALPaoCh1BWdWww8Kztd13GBaY9mMeZX268fOQgECRytiKm-nPQ@mail.gmail.com>
Date: Mon, 4 Nov 2024 15:16:00 +0100
From: Peter Newman <peternewman@...gle.com>
To: Babu Moger <babu.moger@....com>
Cc: corbet@....net, reinette.chatre@...el.com, tglx@...utronix.de, 
	mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com, 
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Subject: Re: [PATCH v9 19/26] x86/resctrl: Add the interface to unassign a MBM counter

Hi Babu,

On Wed, Oct 30, 2024 at 12:25 AM Babu Moger <babu.moger@....com> wrote:
>
> The mbm_cntr_assign mode provides a limited number of hardware counters
> that can be assigned to an RMID, event pair to monitor bandwidth while
> assigned. If all counters are in use, the kernel will show an error
> message: "Out of MBM assignable counters" when a new assignment is
> requested. To make space for a new assignment, users must unassign an
> already assigned counter.
>
> Introduce an interface that allows for the unassignment of counter IDs
> from both the group and the domain. Additionally, ensure that the global
> counter is released if it is no longer assigned to any domains.

This seems unnecessarily restrictive. What's wrong with monitoring
different groups in different domains?


-Peter