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SubjectRe: [PATCH] sched/isolation: Allow "isolcpus=" to skip unknown sub-parameters
On Fri, Feb 14, 2020 at 09:28:25PM +0100, Thomas Gleixner wrote:
> Peter Xu <peterx@redhat.com> writes:
>
> > On Tue, Feb 04, 2020 at 11:16:39AM -0500, Peter Xu wrote:
> >> The "isolcpus=" parameter allows sub-parameters to exist before the
> >> cpulist is specified, and if it sees unknown sub-parameters the whole
> >> parameter will be ignored. This design is incompatible with itself
> >> when we add more sub-parameters to "isolcpus=", because the old
> >> kernels will not recognize the new "isolcpus=" sub-parameters, then it
> >> will invalidate the whole parameter so the CPU isolation will not
> >> really take effect if we start to use the new sub-parameters while
> >> later we reboot into an old kernel. Instead we will see this when
> >> booting the old kernel:
> >>
> >> isolcpus: Error, unknown flag
> >>
> >> The better and compatible way is to allow "isolcpus=" to skip unknown
> >> sub-parameters, so that even if we add new sub-parameters to it the
> >> old kernel will still be able to behave as usual even if with the new
> >> sub-parameter is specified.
> >>
> >> Ideally this patch should be there when we introduce the first
> >> sub-parameter for "isolcpus=", so it's already a bit late. However
> >> late is better than nothing.
> >
> > Ping - Hi, Thomas, do you have any further comment on this patch?
>
> Fine with me.
>
> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

Thanks Thomas!

Does anyone like to pick this up, or does this patch needs more
review?

Thanks,

--
Peter Xu

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