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

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Message-ID: <c3c54172-087e-4a53-bd66-7849402f4a55@amd.com>
Date: Thu, 17 Apr 2025 09:34:46 -0500
From: "Moger, Babu" <babu.moger@....com>
To: Reinette Chatre <reinette.chatre@...el.com>, tony.luck@...el.com,
 peternewman@...gle.com
Cc: corbet@....net, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
 dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
 paulmck@...nel.org, akpm@...ux-foundation.org, thuth@...hat.com,
 rostedt@...dmis.org, ardb@...nel.org, gregkh@...uxfoundation.org,
 daniel.sneddon@...ux.intel.com, jpoimboe@...nel.org,
 alexandre.chartre@...cle.com, pawan.kumar.gupta@...ux.intel.com,
 thomas.lendacky@....com, perry.yuan@....com, seanjc@...gle.com,
 kai.huang@...el.com, xiaoyao.li@...el.com, kan.liang@...ux.intel.com,
 xin3.li@...el.com, ebiggers@...gle.com, xin@...or.com,
 sohil.mehta@...el.com, andrew.cooper3@...rix.com, mario.limonciello@....com,
 linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
 maciej.wieczor-retman@...el.com, eranian@...gle.com
Subject: Re: [PATCH v12 20/26] x86/resctrl: Provide interface to update the
 event configurations

Hi Reinette,

On 4/16/25 13:52, Reinette Chatre wrote:
> Hi Babu,
> 
> On 4/15/25 1:37 PM, Moger, Babu wrote:
>> 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@....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.
> 
> I am not aware of a documented rule that user doc should be in imperative mode. I
> requested imperative tone here because writing in this way helps to remove ambiguity
> and fits with how the rest of the resctrl files are described.
> 
> Looking at this specific addition I realized that there is no initial description of
> what "event_filter" contains and to make things more confusing the term "event" is
> used for both the individual "events" being counted (remote_reads, local_reads, etc.) as
> well as the (what will eventually be dynamic) name for collection of "events" being counted,
> mbm_total_bytes and mbm_local_bytes. 
> 
> Since "event" have been used for mbm_total_bytes and mbm_local_bytes since beginning we
> should try to come up with term that can describe what they are configured with.
> 
> Below is a start of trying to address this but I think more refinement is needed (other
> possible terms for "transactions" could perhaps be "data sources"? ... what do you think?):
> 
> 	"The read/write event_filter file contains the configuration of the event
> 	 that reflects which transactions(?) are being counted by it."
> 

How about?

"The read/write event_filter file contains the configuration of the event
that reflects which memory transactions are being counted by it."


-- 
Thanks
Babu Moger