Re: [PATCH v8 08/25] x86/resctrl: Introduce interface to display number of monitoring counters

[Moger, Babu]

Hi Tony,

On 10/10/24 10:58, Luck, Tony wrote:
>> All good points. How about this text:
>>
>> "num_mbm_cntrs":
>> The number of monitoring counters available for assignment when the
>> architecture supports mbm_cntr_assign mode.
>>
>> Resctrl subsystem provides the interface to count maximum of two memory
>> bandwidth events per group, from a combination of available total and
>> local events. Keeping the current interface, users can enable a maximum of
>> 2 counters per group. User will also have the option to enable only one
>> counter to the group to maximize the number of groups monitored.
> 
> Much better. Looks OK to me.

thanks

> 
> New questions:
> 
> 1) Should resctrl provide a file to tell the user how many free
> counters are available? They can figure it out by counting all the 'l' and 't'
> in "mbm_assign_control" and subtracting that from "num_mbm_cntrs".
> But that seems complex.

We have the information already in r->mon.mbm_cntr_free_map.

How about adding an extra text while printing num_mbm_cntrs?

$ cat /sys/fs/resctrl/info/L3_MON/num_mbm_cntrs
  Total 32, Available 16

There are all global counters, we don't differentiate between sockets just
like number of CLOSIDs.


> 
> 2) Even more so because free counters might be different per socket
> if the user did some "0=tl;1=_" assignments as in one of your examples.
> 
> Maybe a UI like:
> 
> $ cat /sys/fs/resctrl/info/L3_MON/free_mbm_cntrs
> 0=5;1=9
> 
> -Tony
> 
> 

-- 
Thanks
Babu Moger