On Fri, 19 Dec 2025 18:11:35 +0000
Ben Horgan [off-list ref] wrote:

From: James Morse <james.morse@arm.com>

When resctrl wants to read a domain's 'QOS_L3_OCCUP', it needs to allocate
a monitor on the corresponding resource. Monitors are allocated by class
instead of component.

MBM monitors are much more complicated, if there are enough monitors, they
will be pre-allocated and free-running. If ABMC is in use instead then
'some' are pre-allocated in a different way, and need assigning.

Add helpers to allocate a CSU monitor. These helper return an out of range
value for MBM counters.

Allocating a montitor context is expected to block until hardware resources

monitor

become available. This only makes sense for QOS_L3_OCCUP as unallocated MBM
counters are losing data.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
---
Changes since rfc:
USE_RMID_IDX -> USE_PRE_ALLOCATED in comment
Remove unnecessary arch_mon_ctx = NULL

As with some other patches, I'm not taking the time at this point to dig
into all the interactions with resctl as others will cover that much better
than me.

Too much to get done :( 

With that in mind.

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

J