Messages in this thread | | | Date | Thu, 7 Oct 2021 16:06:55 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] x86/apic: reduce cache line misses in __x2apic_send_IPI_mask() |
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On Thu, Oct 07, 2021 at 07:04:09AM -0700, Eric Dumazet wrote: > On Thu, Oct 7, 2021 at 12:29 AM Peter Zijlstra <peterz@infradead.org> wrote: > > > > On Wed, Oct 06, 2021 at 08:17:56PM -0700, Eric Dumazet wrote: > > > +/* __x2apic_send_IPI_mask() possibly needs to read > > > + * x86_cpu_to_logical_apicid for all online cpus in a sequential way. > > > + * Using per cpu variable would cost one cache line per cpu. > > > + */ > > > > Broken comment style.. > > I was not sure and ran checkpatch.pl before submission, but sure. > > > > > > +static u32 x86_cpu_to_logical_apicid[NR_CPUS] __read_mostly; > > > > NR_CPUS is really sad, could this at all be dynamically allocated? Say > > in x2apic_cluster_probe() ? > > Good idea, I will try this. > Hopefully nr_cpu_ids is populated there ?
Lets hope :-), I'm always terminally lost in early bringup. I figure it should be painfully obvious if it goes wrong.
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