linux-kernel - Re: [PATCH v3 41/47] arm_mpam: Generate a configuration for min controls

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Message-ID: <20260113153938.00007d6e@huawei.com>
Date: Tue, 13 Jan 2026 15:39:38 +0000
From: Jonathan Cameron <jonathan.cameron@...wei.com>
To: Ben Horgan <ben.horgan@....com>
CC: <amitsinght@...vell.com>, <baisheng.gao@...soc.com>,
	<baolin.wang@...ux.alibaba.com>, <carl@...amperecomputing.com>,
	<dave.martin@....com>, <david@...nel.org>, <dfustini@...libre.com>,
	<fenghuay@...dia.com>, <gshan@...hat.com>, <james.morse@....com>,
	<kobak@...dia.com>, <lcherian@...vell.com>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
	<peternewman@...gle.com>, <punit.agrawal@....qualcomm.com>,
	<quic_jiles@...cinc.com>, <reinette.chatre@...el.com>,
	<rohit.mathew@....com>, <scott@...amperecomputing.com>,
	<sdonthineni@...dia.com>, <tan.shaopeng@...itsu.com>,
	<xhao@...ux.alibaba.com>, <catalin.marinas@....com>, <will@...nel.org>,
	<corbet@....net>, <maz@...nel.org>, <oupton@...nel.org>,
	<joey.gouly@....com>, <suzuki.poulose@....com>, <kvmarm@...ts.linux.dev>,
	Zeng Heng <zengheng4@...wei.com>
Subject: Re: [PATCH v3 41/47] arm_mpam: Generate a configuration for min
 controls

On Mon, 12 Jan 2026 16:59:08 +0000
Ben Horgan <ben.horgan@....com> wrote:

> From: James Morse <james.morse@....com>
> 
> MPAM supports a minimum and maximum control for memory bandwidth. The
> purpose of the minimum control is to give priority to tasks that are below
> their minimum value. Resctrl only provides one value for the bandwidth
> configuration, which is used for the maximum.
> 
> The minimum control is always programmed to zero on hardware that supports
> it.
> 
> Generate a minimum bandwidth value that is 5% lower than the value provided
> by resctrl. This means tasks that are not receiving their target bandwidth
> can be prioritised by the hardware.
> 
> For component reset reuse the same calculation so that the default is a
> value resctrl can set.
> 
> CC: Zeng Heng <zengheng4@...wei.com>
> Signed-off-by: James Morse <james.morse@....com>
> Signed-off-by: Ben Horgan <ben.horgan@....com>

I'm interested to see how this plays out as a default choice
vs what people elect to run.  Seems harmless to start with this.

Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>