Re: [PATCH v12 20/26] x86/resctrl: Provide interface to update the event configurations

Reinette Chatre
2025-04-16T18:53:05Z

Hi Babu,

On 4/15/25 1:37 PM, Moger, Babu wrote:
> Hi Reinette,
>
> On 4/11/25 17:07, Reinette Chatre wrote:
>> Hi Babu,
>>
>> On 4/3/25 5:18 PM, Babu Moger wrote:
>>> Users can modify the event configuration by writing to the event_filter
>>> interface file. The event configurations for mbm_cntr_assign mode are
>>> located in /sys/fs/resctrl/info/event_configs/.
>>>
>>> Update the assignments of all groups when the event configuration is
>>> modified.
>>>
>>> Example:
>>> $ cd /sys/fs/resctrl/
>>> $ echo "local_reads, local_non_temporal_writes" >
>>> info/L3_MON/counter_configs/mbm_total_bytes/event_filter
>>>
>>> $ cat info/L3_MON/counter_configs/mbm_total_bytes/event_filter
>>> local_reads, local_non_temporal_writes
>>>
>>> Signed-off-by: Babu Moger <babu.moger@amd.com>
>>> ---
>>> v12: New patch to modify event configurations.
>>> ---
>>> Documentation/arch/x86/resctrl.rst | 10 +++
>>> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 115 ++++++++++++++++++++++++-
>>> 2 files changed, 124 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
>>> index 99f9f4b9b501..4e6feba6fb08 100644
>>> --- a/Documentation/arch/x86/resctrl.rst
>>> +++ b/Documentation/arch/x86/resctrl.rst
>>> @@ -335,6 +335,16 @@ with the following files:
>>> # cat /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_local_bytes/event_filter
>>> local_reads, local_non_temporal_writes, local_reads_slow_memory
>>>
>>> + The event configuration can be modified by writing to the event_filter file within
>>> + the configuration directory.
>>
>> Please use imperative tone.
>
> Sure.
>
> Basic question - Should the user doc also be in imperative mode? I thought
> it only applies to commit log.

I am not aware of a documented rule that user doc should be in imperative mode. I
requested imperative tone here because writing in this way helps to remove ambiguity
and fits with how the rest of the resctrl files are described.

Looking at this specific addition I realized that there is no initial description of
what "event_filter" contains and to make things more confusing the term "event" is
used for both the individual "events" being counted (remote_reads, local_reads, etc.) as
well as the (what will eventually be dynamic) name for collection of "events" being counted,
mbm_total_bytes and mbm_local_bytes.

Since "event" have been used for mbm_total_bytes and mbm_local_bytes since beginning we
should try to come up with term that can describe what they are configured with.

Below is a start of trying to address this but I think more refinement is needed (other
possible terms for "transactions" could perhaps be "data sources"? ... what do you think?):

"The read/write event_filter file contains the configuration of the event
that reflects which transactions(?) are being counted by it."

Reinette