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Date:   Wed, 16 Mar 2022 14:50:42 -0700
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Subject: Re: [PATCH v3 13/21] x86/recstrl: Add per-rmid arch private storage
 for overflow and chunks
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To:     James Morse <james.morse@arm.com>, <x86@kernel.org>,
        <linux-kernel@vger.kernel.org>
CC:     Fenghua Yu <fenghua.yu@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        H Peter Anvin <hpa@zytor.com>,
        Babu Moger <Babu.Moger@amd.com>,
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References: <20220217182110.7176-1-james.morse@arm.com>
 <20220217182110.7176-14-james.morse@arm.com>
From:   Reinette Chatre <reinette.chatre@intel.com>
In-Reply-To: <20220217182110.7176-14-james.morse@arm.com>
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Hi James,

Note the subject line: "x86/recstrl" -> "x86/resctrl"

On 2/17/2022 10:21 AM, James Morse wrote:
> A renamed __rmid_read() is intended as the function that an
> architecture agnostic resctrl filesystem driver can use to
> read a value in bytes from a counter. Currently the function returns
> the MBM values in chunks directly from hardware. For bandwidth
> counters the resctrl filesystem uses this to calculate the number of
> bytes ever seen.
> 
> MPAM's scaling of counters can be changed at runtime, reducing the
> resolution but increasing the range. When this is changed the prev_msr
> values need to be converted by the architecture code.
> 
> Add an array for per-rmid private storage. The prev_msr and chunks
> values will move here to allow resctrl_arch_rmid_read() to always
> return the number of bytes read by this counter without assistance
> from the filesystem. The values are moved in later patches when
> the overflow and correction calls are moved into __rmid_read().
> 
> Signed-off-by: James Morse <james.morse@arm.com>

Reinette