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

Moger, Babu
2025-04-15T20:37:48Z

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.

>
>> + ::
>> +
>> + # echo "local_reads, local_non_temporal_writes" >
>> + /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_total_bytes/event_filter
>> +
>> + # cat /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_total_bytes/event_filter
>> + local_reads, local_non_temporal_writes
>> +
>> "max_threshold_occupancy":
>> Read/write file provides the largest value (in
>> bytes) at which a previously used LLC_occupancy
>> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> index b2122a1dd36c..7792455f0b26 100644
>> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> @@ -1926,6 +1926,118 @@ static int event_filter_show(struct kernfs_open_file *of, struct seq_file *seq,
>> return 0;
>> }
>>
>
> Could you please add comments to these new functions to explain what they do?

Sure.

>
>> +static int resctrl_group_assign(struct rdt_resource *r, struct rdtgroup *rdtgrp,
>> + enum resctrl_event_id evtid, u32 evt_cfg)
>> +{
>> + struct rdt_mon_domain *d;
>> + int cntr_id, ret;
>> +
>> + list_for_each_entry(d, &r->mon_domains, hdr.list) {
>> + cntr_id = mbm_cntr_get(r, d, rdtgrp, evtid);
>> + if (cntr_id >= 0 && d->cntr_cfg[cntr_id].evt_cfg != evt_cfg) {
>> + d->cntr_cfg[cntr_id].evt_cfg = evt_cfg;
>> + ret = resctrl_arch_config_cntr(r, d, evtid, rdtgrp->mon.rmid,
>> + rdtgrp->closid, cntr_id, evt_cfg, true);
>> + if (ret) {
>> + rdt_last_cmd_printf("Assign failed event %d domain %d group %s\n",
>> + evtid, d->hdr.id, rdtgrp->kn->name);
>
> Please provide the actual event name to user space. The event IDs are not visible to
> user space.

Sure.

--
Thanks
Babu Moger