Re: [RFC PATCH 3/3] x86/resctrl: Display the RMID and COSID for resctrl groups

[Moger, Babu]

Hi Stephane,

On 1/4/23 00:45, Stephane Eranian wrote:
> On Tue, Jan 3, 2023 at 10:06 PM Yu, Fenghua <fenghua.yu@xxxxxxxxx> wrote:
>> Hi, Babu,
>>
>>> When a user creates a control or monitor group, the CLOSID or RMID are not
>>> visible to the user. These are architecturally defined entities.
>>> There is no harm in displaying these in resctrl groups. Sometimes it can help to
>>> debug the issues.
>> Although "no harm" to show them, it's not useful for generic user either and may
>> cause confusion sometimes. CLOSID and RMID are supposed to be invisible to
>> generic users.
>>
>> Maybe introduce a new resctrl mount option called "debug" and show the files
>> and maybe other future debug info only in debug mode?
>>
> On other non-x86 architectures, these have no meaning or no direct mapping.
> Take ARM MPAM, it is called PARTID and it does not map to either RMID
> or CLOSID, it is combined.
> Why would you call this closid/rmid at the user level?
> You could instead use a more generic name such as mon_hw_id,
> ctrl_hw_id. And on ARM they would be the same.
> Just my suggestion.

Sure. We can change the names to mon_hw_id and ctrl_hw_id.

Thanks

Babu


>
>
>>> Add CLOSID and RMID to the control/monitor groups display in resctrl interface.
>>>
>>>   $cat /sys/fs/resctrl/clos1/closid
>>>   1
>>>   $cat /sys/fs/resctrl/mon_groups/mon1/rmid
>>>   3
>>>
>>> Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
>>> ---
>>>  Documentation/x86/resctrl.rst          |   15 ++++++++++
>>>  arch/x86/kernel/cpu/resctrl/rdtgroup.c |   46
>>> ++++++++++++++++++++++++++++++++
>>>  2 files changed, 61 insertions(+)
>>>
>>> diff --git a/Documentation/x86/resctrl.rst b/Documentation/x86/resctrl.rst
>>> index f26e16412bcb..8520514bc8b5 100644
>>> --- a/Documentation/x86/resctrl.rst
>>> +++ b/Documentation/x86/resctrl.rst
>>> @@ -231,6 +231,14 @@ All groups contain the following files:
>>>       Just like "cpus", only using ranges of CPUs instead of bitmasks.
>>>
>>>
>>> +"rmid":
>>> +     Reading this file shows the resource monitoring id (RMID) for
>>> +     monitoring the resource utilization. Monitoring is performed by
>>> +     tagging each core(or thread) or process via a Resource Monitoring
>>> +     ID (RMID). Kernel assigns a new RMID when a group is created
>>> +     depending on the available RMIDs. Multiple cores(or threads) or
>>> +     processes can share a same RMID in a resctrl domain.
>>> +
>>>  When control is enabled all CTRL_MON groups will also contain:
>>>
>>>  "schemata":
>>> @@ -252,6 +260,13 @@ When control is enabled all CTRL_MON groups will
>>> also contain:
>>>       file. On successful pseudo-locked region creation the mode will
>>>       automatically change to "pseudo-locked".
>>>
>>> +"closid":
>>> +     Reading this file shows the Class of Service (CLOS) id which acts
>>> +     as a resource control tag on which the resources can be throttled.
>>> +     Kernel assigns a new CLOSID a control group is created depending
>>> +     on the available CLOSIDs. Multiple cores(or threads) or processes
>>> +     can share a same CLOSID in a resctrl domain.
>>> +
>>>  When monitoring is enabled all MON groups will also contain:
>>>
>>>  "mon_data":
>>> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>>> b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>>> index 0d71ed22cfa9..98b4798e5cae 100644
>>> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>>> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>>> @@ -769,6 +769,38 @@ static int rdtgroup_tasks_show(struct kernfs_open_file
>>> *of,
>>>       return ret;
>>>  }
>>>
>>> +static int rdtgroup_closid_show(struct kernfs_open_file *of,
>>> +                             struct seq_file *s, void *v)
>>> +{
>>> +     struct rdtgroup *rdtgrp;
>>> +     int ret = 0;
>>> +
>>> +     rdtgrp = rdtgroup_kn_lock_live(of->kn);
>>> +     if (rdtgrp)
>>> +             seq_printf(s, "%u\n", rdtgrp->closid);
>>> +     else
>>> +             ret = -ENOENT;
>>> +     rdtgroup_kn_unlock(of->kn);
>>> +
>>> +     return ret;
>>> +}
>>> +
>>> +static int rdtgroup_rmid_show(struct kernfs_open_file *of,
>>> +                           struct seq_file *s, void *v)
>>> +{
>>> +     struct rdtgroup *rdtgrp;
>>> +     int ret = 0;
>>> +
>>> +     rdtgrp = rdtgroup_kn_lock_live(of->kn);
>>> +     if (rdtgrp)
>>> +             seq_printf(s, "%u\n", rdtgrp->mon.rmid);
>>> +     else
>>> +             ret = -ENOENT;
>>> +     rdtgroup_kn_unlock(of->kn);
>>> +
>>> +     return ret;
>>> +}
>>> +
>>>  #ifdef CONFIG_PROC_CPU_RESCTRL
>>>
>>>  /*
>>> @@ -1593,6 +1625,20 @@ static struct rftype res_common_files[] = {
>>>               .seq_show       = rdtgroup_size_show,
>>>               .fflags         = RF_CTRL_BASE,
>>>       },
>>> +     {
>>> +             .name           = "closid",
>>> +             .mode           = 0444,
>>> +             .kf_ops         = &rdtgroup_kf_single_ops,
>>> +             .seq_show       = rdtgroup_closid_show,
>>> +             .fflags         = RF_CTRL_BASE,
>>> +     },
>>> +     {
>>> +             .name           = "rmid",
>>> +             .mode           = 0444,
>>> +             .kf_ops         = &rdtgroup_kf_single_ops,
>>> +             .seq_show       = rdtgroup_rmid_show,
>>> +             .fflags         = RFTYPE_BASE,
>>> +     },
>>>
>>>  };
>>>
>>>
>> Thanks.
>>
>> -Fenghua

-- 
Thanks
Babu Moger