Messages in this thread | | | Date | Tue, 31 Mar 2020 16:57:59 -0400 | From | Peter Xu <> | Subject | Re: [PATCH] sched/isolation: Allow "isolcpus=" to skip unknown sub-parameters |
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On Mon, Mar 09, 2020 at 11:19:17AM -0400, Peter Xu wrote: > 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?
Another gentle ping with the hope that this patch can be picked up.
It's a very simple patch, but I really hope it can be in asap because the latter means the more kernel versions will be affected by this isolcpus incompatibility defect (and imo should consider stable too).
Thanks.
-- Peter Xu
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