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Message-ID: <d29a28c8-1180-45ec-bd87-d2e8a8124c42@intel.com>
Date: Tue, 5 Mar 2024 09:12:03 -0800
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Subject: Re: [PATCH v2 00/17] x86/resctrl : Support AMD Assignable Bandwidth
 Monitoring Counters (ABMC)
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To: <babu.moger@amd.com>, James Morse <james.morse@arm.com>, <corbet@lwn.net>,
	<fenghua.yu@intel.com>, <tglx@linutronix.de>, <mingo@redhat.com>,
	<bp@alien8.de>, <dave.hansen@linux.intel.com>, Peter Newman
	<peternewman@google.com>
CC: <x86@kernel.org>, <hpa@zytor.com>, <paulmck@kernel.org>,
	<rdunlap@infradead.org>, <tj@kernel.org>, <peterz@infradead.org>,
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	<kirill.shutemov@linux.intel.com>, <jithu.joseph@intel.com>,
	<kai.huang@intel.com>, <kan.liang@linux.intel.com>,
	<daniel.sneddon@linux.intel.com>, <pbonzini@redhat.com>,
	<sandipan.das@amd.com>, <ilpo.jarvinen@linux.intel.com>,
	<maciej.wieczor-retman@intel.com>, <linux-doc@vger.kernel.org>,
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References: <20231201005720.235639-1-babu.moger@amd.com>
 <cover.1705688538.git.babu.moger@amd.com>
 <2f373abf-f0c0-4f5d-9e22-1039a40a57f0@arm.com>
 <474ebe02-2d24-4ce3-b26a-46c520efd453@amd.com>
 <b6bb6a59-67c2-47bc-b8d3-04cf8fd21219@intel.com>
 <3fe3f235-d8a6-453b-b69d-6b7f81c07ae1@amd.com>
 <9b94b97e-4a8c-415e-af7a-d3f832592cf9@intel.com>
 <1ae73c9a-cec4-4496-86c6-3ffcef7940d6@amd.com>
 <32a588e2-7b09-4257-b838-4268583a724d@intel.com>
 <088878bd-7533-492d-838c-6b39a93aad4d@amd.com>
 <9b20589b-6220-4ae7-bfc4-4a826b7114b1@intel.com>
 <5ddb7031-a828-4001-bfdf-5477cb85e9ed@amd.com>
 <1738493b-3248-4c9e-82a8-1599a033440d@intel.com>
 <369ab28a-f3fa-4359-8e73-4dcf214c9b6e@amd.com>
 <54687d59-d0e4-4fe7-b25f-dc1fead01ea1@intel.com>
 <11487a31-908e-d474-50c6-65617d417deb@amd.com>
 <c73f444b-83a1-4e9a-95d3-54c5165ee782@intel.com>
 <55b545fd-2851-0d0f-ac37-ec59838fb4b4@amd.com>
 <1f366890-d9ff-4ac4-9af9-1ea3128a87fc@intel.com>
 <41ca7504-c3fb-ddb6-e149-4ff82019d678@amd.com>
From: Reinette Chatre <reinette.chatre@intel.com>
In-Reply-To: <41ca7504-c3fb-ddb6-e149-4ff82019d678@amd.com>
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Hi Babu,

On 3/4/2024 2:24 PM, Moger, Babu wrote:

> Based on our discussion, I am listing few examples here. Let me know if I missed something.
> 
>   mount  -t resctrl resctrl /sys/fs/resctrl/

When creating examples it may help to accompany it with an overview of
which groups exist.

> 
> 1. Assign both local and total counters to default group on domain 0 and 1.
>    $echo "//00=lt;01=lt" > /sys/fs/resctrl/info/L3_MON/mbm_assign_control
> 
>    $cat /sys/fs/resctrl/info/L3_MON/mbm_assign_control
>    //00=lt;01=lt

I also think it will be useful to always print a small header that guides
the interpretation. For example,

$ cat mbm_assign_control 
#control_group/monitor_group/flags
..

> 
> 2. Assign a total event to mon group inside the default group for both domain 0 and 1.
> 
>    $mkdir /sys/fs/resctrl/mon_groups/mon_a
>    $echo "/mon_a/00+t;01+t" > /sys/fs/resctrl/info/L3_MON/mbm_assign_control
> 
>    $cat /sys/fs/resctrl/info/L3_MON/mbm_assign_control
>    //00=lt;01=lt
>    /mon_a/00=t;01=t

For an example of "+" I think understanding the output will be easier if the "before" view with
existing flags is available. For example,
if it was
   $cat /sys/fs/resctrl/info/L3_MON/mbm_assign_control
   #control_group/monitor_group/flags
   /mon_a/00=l;01=l

then
   $echo "/mon_a/00+t;01+t" > /sys/fs/resctrl/info/L3_MON/mbm_assign_control

would result in:
   $cat /sys/fs/resctrl/info/L3_MON/mbm_assign_control
   #control_group/monitor_group/flags
   /mon_a/00=lt;01=lt

An example like above would make it easier to understand how it is different
from using "=" like in example 1.

> 
> 3. Assign a local event to non-default control mon group both domain 0 and 1.
>    $mkdir /sys/fs/resctrl/ctrl_a
>    $echo "/ctrl_a/00=l;01=l"  > /sys/fs/resctrl/info/L3_MON/mbm_assign_control

I think this should be:
	$echo "ctrl_a//00=l;01=l"  > /sys/fs/resctrl/info/L3_MON/mbm_assign_control

> 
>    $cat /sys/fs/resctrl/info/L3_MON/mbm_assign_control
>    //00=lt;01=lt
>    /mon_a/00=t;01=t
>    /ctrl_a/00=l;01=l

     ctrl_a//00=l;01=l

> 
> 4. Assign a both counters to mon group inside another control group(non-default).
>    $mkdir /sys/fs/resctrl/ctrl_a/mon_ab/

Above will not work.

     $ mkdir /sys/fs/resctrl/ctrl_a
     $ mkdir /sys/fs/resctrl/ctrl_a/mon_groups/mon_ab

>    $echo "ctrl_a/mon_ab/00=lt;01=lt" > /sys/fs/resctrl/nfo/L3_MON/mbm_assign_contro

(watch out for typos in examples)

> 
>    $cat /sys/fs/resctrl/info/L3_MON/mbm_assign_control
>    //00=lt;01=lt
>    /mon_a/00=t;01=t
>    /ctrl_a/00=l;01=l
>    ctrl_a/mon_ab/00=lt;01=lt
> 
> 5. Unassign a counter to mon group inside another control group(non-default).
>    $echo "ctrl_a/mon_ab/00-l;01-l" > /sys/fs/resctrl/nfo/L3_MON/mbm_assign_control
> 
>   $cat /sys/fs/resctrl/info/L3_MON/mbm_assign_control
>   //00=lt;01=lt
>   /mon_a/00=t;01=t
>   /ctrl_a/00=l;01=l
>   ctrl_a/mon_ab/00=t;01=t

ack.

> 
> 6. Unassign all the counters on a specific group.
>    $echo "ctrl_a/mon_ab/00=_" > /sys/fs/resctrl/nfo/L3_MON/mbm_assign_control

(watch for typos)

Note that this only did unassign on domain 0.

> 
>    $cat /sys/fs/resctrl/info/L3_MON/mbm_assign_control
>    //00=lt;01=lt
>    /mon_a/00=t;01=t
>    /ctrl_a/00=l;01=l
>    ctrl_a/mon_ab/00=_;01=_

     ctrl_a/mon_ab/00=_;01=t

To address some earlier requirements I think it will be helpful to also
show an example of multiple groups changed with a single write.

Reinette