Re: [RFC PATCH v3 00/17] x86/resctrl : Support AMD Assignable Bandwidth Monitoring Counters (ABMC)

Moger, Babu
2024-04-22T20:44:32Z

Hi Dave,

On 4/22/24 11:34, Dave Martin wrote:
> Hi Babu,
>
> On Thu, Apr 04, 2024 at 03:02:45PM -0500, Moger, Babu wrote:
>> Hi Peter,
>>
>>
>> On 4/4/24 14:08, Peter Newman wrote:
>>> Hi Babu,
>>>
>>> On Thu, Mar 28, 2024 at 6:07 PM Babu Moger <babu.moger@amd.com> wrote:
>>>> The list follows the following format:
>>>>
>>>> * Default CTRL_MON group:
>>>> "//<domain_id>=<assignment_flags>"
>>>>
>>>> * Non-default CTRL_MON group:
>>>> "<CTRL_MON group>//<domain_id>=<assignment_flags>"
>>>>
>>>> * Child MON group of default CTRL_MON group:
>>>> "/<MON group>/<domain_id>=<assignment_flags>"
>>>>
>>>> * Child MON group of non-default CTRL_MON group:
>>>> "<CTRL_MON group>/<MON group>/<domain_id>=<assignment_flags>"
>>>>
>>>> Assignment flags can be one of the following:
>>>>
>>>> t MBM total event is assigned
>>>> l MBM local event is assigned
>>>> tl Both total and local MBM events are assigned
>>>> _ None of the MBM events are assigned
>>>>
>>>> Examples:
>>>>
>>>> # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_control
>>>> non_defult_group//0=tl;1=tl;2=tl;3=tl;4=tl;5=tl;6=tl;7=tl;
>>>> non_defult_group/non_default_mon1/0=tl;1=tl;2=tl;3=tl;4=tl;5=tl;6=tl;7=tl;
>>>> //0=tl;1=tl;2=tl;3=tl;4=tl;5=tl;6=tl;7=tl;
>>>> /default_mon1/0=tl;1=tl;2=tl;3=tl;4=tl;5=tl;6=tl;7=tl;
>>>>
>>>> There are four groups and all the groups have local and total event assigned.
>>>>
>>>> "//" - This is a default CONTROL MON group
>>>>
>>>> "non_defult_group//" - This is non default CONTROL MON group
>>>>
>>>> "/default_mon1/" - This is Child MON group of the defult group
>>>>
>>>> "non_defult_group/non_default_mon1/" - This is child MON group of the non default group
>>>>
>>>> =tl means both total and local events are assigned.
>>>
>>> I recall there was supposed to be a way to perform the same update on
>>> all domains together so that it isn't tedious to not do per-domain
>>
>> Yes. Correct. Reinette suggested to have "no domains" means ALL the domains.
>
> Would "*" be more intuitive?

We could. But I don't see the need for wildcard ("*") or ranges and
complexity that comes with that.

Even in schemata processing we don't use the wildcard or ranges and also
there is no mention of that in documentation.
https://www.kernel.org/doc/Documentation/x86/resctrl.rst

Domains(or nodes) are processed one by one. Some examples.

# cat schemata
SMBA:0=2048;1=2048;2=2048;3=2048
MB:0=2048;1=2048;2=2048;3=2048
L3:0=ffff;1=ffff;2=ffff;3=ffff

# echo "SMBA:1=64" > schemata
# cat schemata
SMBA:0=2048;1= 64;2=2048;3=2048
MB:0=2048;1=2048;2=2048;3=2048
L3:0=ffff;1=ffff;2=ffff;3=ffff

>
> Whatever is done here to describe the "wildcard node", would it be worth
> having the node field parse the same way in the "schemata" files?
>
> Is there any merit in having range match expressions, e.g. something like
>
> 0-3,8-11=foo;4-7,12-*=bar
>
> (The latter is obvious feature creep though, so a real use case for this
> would be needed to justify it. I don't have one right now...)
>
> [...]
>
> Cheers
> ---Dave

--
Thanks
Babu Moger