linux-kernel - Re: [RFC 2/2] cgroup: sev: Miscellaneous cgroup documentation.

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Date:   Fri, 19 Feb 2021 11:02:41 -0800
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Vipin Sharma <vipinsh@...gle.com>, tj@...nel.org,
        thomas.lendacky@....com, brijesh.singh@....com, jon.grimm@....com,
        eric.vantassell@....com, pbonzini@...hat.com, hannes@...xchg.org,
        frankja@...ux.ibm.com, borntraeger@...ibm.com
Cc:     corbet@....net, seanjc@...gle.com, vkuznets@...hat.com,
        wanpengli@...cent.com, jmattson@...gle.com, joro@...tes.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        gingell@...gle.com, rientjes@...gle.com, dionnaglaze@...gle.com,
        kvm@...r.kernel.org, x86@...nel.org, cgroups@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC 2/2] cgroup: sev: Miscellaneous cgroup documentation.

Hi,

On 2/18/21 11:55 AM, Vipin Sharma wrote:
> Documentation of miscellaneous cgroup controller. This new controller is
> used to track and limit usage of scalar resources.
> 
> Signed-off-by: Vipin Sharma <vipinsh@...gle.com>
> Reviewed-by: David Rientjes <rientjes@...gle.com>
> ---
>  Documentation/admin-guide/cgroup-v1/misc.rst |  1 +
>  Documentation/admin-guide/cgroup-v2.rst      | 64 +++++++++++++++++++-
>  2 files changed, 63 insertions(+), 2 deletions(-)
>  create mode 100644 Documentation/admin-guide/cgroup-v1/misc.rst
> 
> diff --git a/Documentation/admin-guide/cgroup-v1/misc.rst b/Documentation/admin-guide/cgroup-v1/misc.rst
> new file mode 100644
> index 000000000000..8e9e9311daeb
> --- /dev/null
> +++ b/Documentation/admin-guide/cgroup-v1/misc.rst
> @@ -0,0 +1 @@
> +/Documentation/admin-guide/cgroup-v2.rst
What is the purpose of this (above) file?

> diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
> index 1de8695c264b..1a41a3623b9b 100644
> --- a/Documentation/admin-guide/cgroup-v2.rst
> +++ b/Documentation/admin-guide/cgroup-v2.rst
> @@ -63,8 +63,11 @@ v1 is available under :ref:`Documentation/admin-guide/cgroup-v1/index.rst <cgrou
>         5-7-1. RDMA Interface Files
>       5-8. HugeTLB
>         5.8-1. HugeTLB Interface Files
> -     5-8. Misc
> -       5-8-1. perf_event
> +     5-9. Misc
> +       5.9-1 Miscellaneous cgroup Interface Files
> +       5.9-2 Migration and Ownership
> +     5-10. Others
> +       5-10-1. perf_event
>       5-N. Non-normative information
>         5-N-1. CPU controller root cgroup process behaviour
>         5-N-2. IO controller root cgroup process behaviour
> @@ -2161,6 +2164,63 @@ HugeTLB Interface Files
>  	generated on this file reflects only the local events.
>  
>  Misc
> +--------------
> +
> +The Miscellaneous cgroup provides the resource allocation and tracking
> +mechanism for the scalar resources which cannot be abstracted like the other
> +cgroup resources. Controller is enabled by the CONFIG_CGROUP_MISC config
> +option.
> +
> +The first two resources added to the miscellaneous controller are Secure
> +Encrypted Virtualization (SEV) ASIDs and SEV - Encrypted State (SEV-ES) ASIDs.
> +These limited ASIDs are used for encrypting virtual machines memory on the AMD
> +platform.
> +
> +Misc Interface Files
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +Miscellaneous controller provides 3 interface files:
> +
> +  misc.capacity
> +        A read-only flat-keyed file shown only in the root cgroup.  It shows
> +        miscellaneous scalar resources available on the platform along with
> +        their quantities::
> +	  $ cat misc.capacity
> +	  sev 50
> +	  sev_es 10
> +
> +  misc.current
> +        A read-only flat-keyed file shown in the non-root cgroups.  It shows
> +        the current usage of the resources in the cgroup and its children.::
> +	  $ cat misc.current
> +	  sev 3
> +	  sev_es 0
> +
> +  misc.max
> +        A read-write flat-keyed file shown in the non root cgroups. Allowed
> +        maximum usage of the resources in the cgroup and its children.::
> +	  $ cat misc.max
> +	  sev max
> +	  sev_es 4
> +
> +	Limit can be set by::
> +	  # echo sev 1 > misc.max
> +
> +	Limit can be set to max by::
> +	  # echo sev max > misc.max
> +
> +        Limits can be set more than the capacity value in the misc.capacity

                             higher than

> +        file.
> +
> +Migration and Ownership
> +~~~~~~~~~~~~~~~~~~~~~~~
> +
> +A miscellaneous scalar resource is charged to the cgroup in which it is used
> +first, and stays charged to that cgroup until that resource is freed. Migrating
> +a process to a different cgroup do not move the charge to the destination

                                   does

> +cgroup where the process has moved.
> +
> +Others
>  ----

That underline is too short for "Others".

>  
>  perf_event
> 

Try building this doc file, please.

next-20210219/Documentation/admin-guide/cgroup-v2.rst:2196: WARNING: Unexpected indentation.
next-20210219/Documentation/admin-guide/cgroup-v2.rst:2203: WARNING: Unexpected indentation.
next-20210219/Documentation/admin-guide/cgroup-v2.rst:2210: WARNING: Unexpected indentation.
next-20210219/Documentation/admin-guide/cgroup-v2.rst:2232: WARNING: Title underline too short.

Others
----
next-20210219/Documentation/admin-guide/cgroup-v2.rst:2232: WARNING: Title underline too short.


I think that the first 3 warnings are due to missing a blank line after ::
or they could have something to do with mixed tabs and spaces in the misc.*
properties descriptions.


thanks.
-- 
~Randy