linux-kernel - Re: [PATCH v11 25/31] fs,x86/resctrl: Compute number of RMIDs as minimum across resources

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Message-ID: <49d86b88-f785-4540-9806-b5d635e2b618@intel.com>
Date: Fri, 3 Oct 2025 17:10:35 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Tony Luck <tony.luck@...el.com>, Fenghua Yu <fenghuay@...dia.com>, "Maciej
 Wieczor-Retman" <maciej.wieczor-retman@...el.com>, Peter Newman
	<peternewman@...gle.com>, James Morse <james.morse@....com>, Babu Moger
	<babu.moger@....com>, Drew Fustini <dfustini@...libre.com>, Dave Martin
	<Dave.Martin@....com>, Chen Yu <yu.c.chen@...el.com>
CC: <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
	<patches@...ts.linux.dev>
Subject: Re: [PATCH v11 25/31] fs,x86/resctrl: Compute number of RMIDs as
 minimum across resources

Hi Tony,

Please use a consistent subject prefix (x86,fs/resctrl) when patch changes both arch
and fs code.

On 9/25/25 1:03 PM, Tony Luck wrote:
> resctrl assumes that only the L3 resource supports monitor events, so
> it simply takes the rdt_resource::num_rmid from RDT_RESOURCE_L3 as
> the system's number of RMIDs.
> 
> The addition of telemetry events in a different resource breaks that
> assumption.
> 
> Compute the number of available RMIDs as the minimum value across
> all mon_capable resources (analogous to how the number of CLOSIDs
> is computed across alloc_capable resources).
> 
> Note that mount time enumeration of the telemetry resource means that
> this number can be reduced. If this happens, then some memory will
> be wasted as the allocations for rdt_l3_mon_domain::mbm_states[] and
> rdt_l3_mon_domain::rmid_busy_llc created during resctrl initialization
> will be larger than needed.
> 
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---

| Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>

Reinette