linux-kernel - Re: [PATCH v5 20/20] x86/resctrl: Introduce interface to modify assignment states of the groups

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Message-ID: <CALPaoCjL92Jwm=Ynt+pEpSt5KLVxnJL8KOKymZ=WP+cUufy_Uw@mail.gmail.com>
Date: Wed, 24 Jul 2024 17:03:53 -0700
From: Peter Newman <peternewman@...gle.com>
To: Babu Moger <babu.moger@....com>
Cc: corbet@....net, fenghua.yu@...el.com, reinette.chatre@...el.com, 
	tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, 
	dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com, 
	paulmck@...nel.org, rdunlap@...radead.org, tj@...nel.org, 
	peterz@...radead.org, yanjiewtw@...il.com, kim.phillips@....com, 
	lukas.bulwahn@...il.com, seanjc@...gle.com, jmattson@...gle.com, 
	leitao@...ian.org, jpoimboe@...nel.org, rick.p.edgecombe@...el.com, 
	kirill.shutemov@...ux.intel.com, jithu.joseph@...el.com, kai.huang@...el.com, 
	kan.liang@...ux.intel.com, daniel.sneddon@...ux.intel.com, 
	pbonzini@...hat.com, sandipan.das@....com, ilpo.jarvinen@...ux.intel.com, 
	maciej.wieczor-retman@...el.com, linux-doc@...r.kernel.org, 
	linux-kernel@...r.kernel.org, eranian@...gle.com, james.morse@....com
Subject: Re: [PATCH v5 20/20] x86/resctrl: Introduce interface to modify
 assignment states of the groups

Hi Babu,

On Wed, Jul 3, 2024 at 2:51 PM Babu Moger <babu.moger@....com> wrote:
>
> Introduce the interface to enable events in ABMC mode.
>
> Events can be enabled or disabled by writing to file
> /sys/fs/resctrl/info/L3_MON/mbm_control
>
> Format is similar to the list format with addition of op-code for the
> assignment operation.
>  "<CTRL_MON group>/<MON group>/<op-code><flags>"
>
> Format for specific type of groups:
>
>  * Default CTRL_MON group:
>          "//<domain_id><op-code><flags>"
>
>  * Non-default CTRL_MON group:
>          "<CTRL_MON group>//<domain_id><op-code><flags>"
>
>  * Child MON group of default CTRL_MON group:
>          "/<MON group>/<domain_id><op-code><flags>"
>
>  * Child MON group of non-default CTRL_MON group:
>          "<CTRL_MON group>/<MON group>/<domain_id><op-code><flags>"

Just a reminder, Reinette and I had discussed[1] omitting the
domain_id for performing the same operation on all domains.

I would really appreciate this, otherwise our most typical operations
could be really tedious and needlessly serialized.

# cat mbm_control
//0=tl;1=tl;2=tl;3=tl;4=tl;5=tl;6=tl;7=tl;8=tl;9=tl;10=tl;11=tl;12=tl;13=tl;14=tl;15=tl;16=tl;17=tl;18=tl;19=tl;20=tl;21=tl;22=tl;23=tl;24=tl;25=tl;26=tl;27=tl;28=tl;29=tl;30=tl;31=tl;
# echo '//-l' > mbm_control
-bash: echo: write error: Invalid argument
# cat ../last_cmd_status
Missing domain id

If you can't get to it in this series, I'll push a
scalability-oriented series after the basic assignment support is
merged.

Thanks!
-Peter

[1] https://lore.kernel.org/lkml/CALPaoChcJq5zoPchB2j0aM+nZpQe1xoo7w2QQUjtH+c58Yyxag@mail.gmail.com/