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SubjectRe: [PATCH 2/5] x86/intel_rdt: Improvements to parsing schemata
On Fri, 10 Mar 2017, Shivappa Vikas wrote:
> On Fri, 10 Mar 2017, Thomas Gleixner wrote:
> > It's fine to display them in a defined order, but there is no point to
> > enforce the ordering on write.
> >
> > The real question here is whether we really have to write every line on
> > every update. IMO it's sufficient to write a single resource line and not
> > require to update all resources every time.
>
> Ok in that case we can drop this. because my thought was that user wants to
> see the contents he wrote when he overwrites the whole file like below , IOW
> its wierd for user to do
>
> # echo "L3:0=0xff;1=0xf0" > /sys/fs/resctrl/schemata
> then
>
> # cat /sys/fs/resctrl/schemata
> L3:0=0xff;1=0xf0
> L2:0=0xff;1=0xf0
> MB:....
>
> But he did not write the L2,MB when he did an overwrite of the whole file.

Well, we have several options to tackle this:

1) Have schemata files for each resource

schemata_l2, _l3 _mb

2) Request a full overwrite every time (all entries required)

That still does not require ordering

3) Allow full overwrite and 'append' mode

echo "...." > schemata

Overwrites the whole file. It does not require all entries to be
supplied. Non supplied entries are reset to default

echo "...." >> schemata

"Appends" the supplied entries by overwriting the existing ones.

My favourite would be #1, but I have no strong opinions other than not
caring about resource write ordering for #2 and #3.

Thanks,

tglx

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