Re: [PATCH v10 16/24] x86/resctrl: Add interface to the assign counter

[Moger, Babu]

Hi Reinette,

On 12/19/2024 3:12 PM, Reinette Chatre wrote:
> Hi Babu,
>
> On 12/19/24 11:45 AM, Moger, Babu wrote:
> > Hi Reinette,
> >
> > On 12/18/2024 4:01 PM, Reinette Chatre wrote:
> > > On 12/13/24 8:54 AM, Moger, Babu wrote:
> > > > On 12/13/2024 10:24 AM, Luck, Tony wrote:
> > > > > > It is right thing to continue assignment if one of the domain is out of
> > > > > > counters. In that case how about we save the error(say error_domain) and
> > > > > > continue. And finally return success if both ret and error_domain are zeros.
> > > > > >
> > > > > >       return ret ?  ret : error_domain:
> > > > >
> > > > > If there are many domains, then you might have 3 succeed and 5 fail.
> > > > >
> > > > > I think the best you can do is return success if everything succeeded
> > > > > and an error if any failed.
> > > >
> > > > Yes. The above check should take care of this case.
> > >
> > > If I understand correctly "error_domain" can capture the ID of
> > > a single failing domain. If there are multiple failing domains like
> > > in Tony's example then "error_domain" will not be accurate and thus
> > > can never be trusted. Instead of a single check of a failure user
> > > space is then forced to parse the more complex "mbm_assign_control"
> > > file to learn what succeeded and failed.
> > >
> > > Would it not be simpler to process sequentially and then fail on
> > > first error encountered with detailed error message? With that
> > > user space can determine exactly which portion of request
> > > succeeded and which portion failed.
> >
> > One more option is to print the error for each failure and continue. And finally return error.
> >
> > "Group mon1, domain:1 Out of MBM counters"
> >
> > We have the error information as well as the convenience of assignment on domains where counters are available when user is working with "*"(all domains).
>
> This may be possible. Please keep in mind that any errors have to be
> easily consumed in an automated way to support the user space tools
> that interact with resctrl. I do not think we have thus far focused
> on the "last_cmd_status" buffer as part of the user space ABI so this opens
> up more considerations.
>
> At this time the error handling of "all domains" does not seem to be
> consistent and obvious to user space. From what I can tell the
> implementation continues on to the next domain if one domain is out
> of counters but it exits immediately if a counter cannot be configured
> on a particular domain.

Yes. We can handle both the errors in the same way.

> > Note: I will be out of office starting next week Until Jan 10.
>
> Thank you for letting me know. I am currently reviewing this series
> and will post feedback by tomorrow.

Sure. Thanks. I will try to get to some of it at least. The review 
comments which needs investigation may have to wait. Lets see.

Thanks
Babu