linux-kernel - Re: [PATCH v9 14/26] x86/resctrl: Introduce interface to display number of free counters

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Message-ID: <9a536685-d0e8-4c0a-b3d7-b0cdc3553903@amd.com>
Date: Mon, 4 Nov 2024 11:31:10 -0600
From: "Moger, Babu" <babu.moger@....com>
To: Peter Newman <peternewman@...gle.com>
Cc: corbet@....net, reinette.chatre@...el.com, tglx@...utronix.de,
 mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
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Subject: Re: [PATCH v9 14/26] x86/resctrl: Introduce interface to display
 number of free counters

Hi Peter,

On 11/4/24 08:14, Peter Newman wrote:
> Hi Babu,
> 
> On Wed, Oct 30, 2024 at 12:24 AM Babu Moger <babu.moger@....com> wrote:
>>
>> Provide the interface to display the number of free monitoring counters
>> available for assignment in each doamin when mbm_cntr_assign is supported.
>>
>> Signed-off-by: Babu Moger <babu.moger@....com>
>> ---
>> v9: New patch.
>> ---
>>  Documentation/arch/x86/resctrl.rst     |  4 ++++
>>  arch/x86/kernel/cpu/resctrl/monitor.c  |  1 +
>>  arch/x86/kernel/cpu/resctrl/rdtgroup.c | 33 ++++++++++++++++++++++++++
>>  3 files changed, 38 insertions(+)
>>
>> diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
>> index 2f3a86278e84..2bc58d974934 100644
>> --- a/Documentation/arch/x86/resctrl.rst
>> +++ b/Documentation/arch/x86/resctrl.rst
>> @@ -302,6 +302,10 @@ with the following files:
>>         memory bandwidth tracking to a single memory bandwidth event per
>>         monitoring group.
>>
>> +"available_mbm_cntrs":
>> +       The number of free monitoring counters available assignment in each domain
>> +       when the architecture supports mbm_cntr_assign mode.
> 
> It seems you need to clarify that counters are only available to a
> domain when they're available in all domains:

Yes. Makes sense.

> 
> resctrl# for i in `seq 100`; do
>> mkdir mon_groups/m${i}
>> done
> resctrl# cat info/L3_MON/available_mbm_cntrs
> 0=0;1=0;2=0;3=0;4=0;5=0;6=0;7=0;8=0;9=0;10=0;11=0;12=0;16=0;17=0;18=0;19=0;20=0;21=0;22=0;23=0;24=0;25=0;26=0;27=0;28=0
> 
> resctrl# cd info/L3_MON/
> L3_MON# echo '/m1/0=_' > mbm_assign_control
> L3_MON# cat available_mbm_cntrs
> 0=2;1=0;2=0;3=0;4=0;5=0;6=0;7=0;8=0;9=0;10=0;11=0;12=0;16=0;17=0;18=0;19=0;20=0;21=0;22=0;23=0;24=0;25=0;26=0;27=0;28=0
> L3_MON# echo '/m16/0+t' > mbm_assign_control
> -bash: echo: write error: Invalid argument
> L3_MON# cat ../last_cmd_status
> Out of MBM assignable counters
> Assign operation '+t' failed on the group /m16/
> 
> L3_MON# rmdir ../../mon_groups/m1
> L3_MON# cat available_mbm_cntrs
> 0=2;1=2;2=2;3=2;4=2;5=2;6=2;7=2;8=2;9=2;10=2;11=2;12=2;16=2;17=2;18=2;19=2;20=2;21=2;22=2;23=2;24=2;25=2;26=2;27=2;28=2
> L3_MON# echo '/m16/0+t' > mbm_assign_control
> L3_MON#
> 

Test case looks good to me. Thanks for trying out.

-- 
Thanks
Babu Moger