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Date: Mon, 6 Oct 2025 15:57:16 +0100
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Subject: Re: [PATCH v2 22/29] arm_mpam: Add helpers to allocate monitors
To: Jonathan Cameron <jonathan.cameron@huawei.com>
Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
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 D Scott Phillips OS <scott@os.amperecomputing.com>,
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References: <20250910204309.20751-1-james.morse@arm.com>
 <20250910204309.20751-23-james.morse@arm.com>
 <20250912141123.000068e2@huawei.com>
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From: James Morse <james.morse@arm.com>
In-Reply-To: <20250912141123.000068e2@huawei.com>
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Hi Jonathan,

On 12/09/2025 14:11, Jonathan Cameron wrote:
> On Wed, 10 Sep 2025 20:43:02 +0000
> James Morse <james.morse@arm.com> wrote:
> 
>> MPAM's MSC support a number of monitors, each of which supports
>> bandwidth counters, or cache-storage-utilisation counters. To use
>> a counter, a monitor needs to be configured. Add helpers to allocate
>> and free CSU or MBWU monitors.
>>
>> Signed-off-by: James Morse <james.morse@arm.com>
>> Reviewed-by: Ben Horgan <ben.horgan@arm.com>
> 
> One minor requested change inline that will probably otherwise get picked
> up by someone's cleanup script
> 
> Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>

Thanks!


>> diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h
>> index 326ba9114d70..81c4c2bfea3d 100644
>> --- a/drivers/resctrl/mpam_internal.h
>> +++ b/drivers/resctrl/mpam_internal.h

>> +static inline int mpam_alloc_mbwu_mon(struct mpam_class *class)
>> +{
>> +	struct mpam_props *cprops = &class->props;
>> +
>> +	if (!mpam_has_feature(mpam_feat_msmon_mbwu, cprops))
>> +		return -EOPNOTSUPP;
>> +
>> +	return ida_alloc_range(&class->ida_mbwu_mon, 0,
>> +			       cprops->num_mbwu_mon - 1, GFP_KERNEL);
> 
> ida_alloc_max() - which is just a wrapper that sets the minimum to 0
> but none the less perhaps conveys things slightly better.

Sure - I didn't spot that when I did this.


Thanks,

James