Messages in this thread | | | Date | Tue, 1 Oct 2002 11:03:05 +0530 | From | Dipankar Sarma <> | Subject | Re: [patch] smptimers, old BH removal, tq-cleanup, 2.5.39 |
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On Tue, Oct 01, 2002 at 05:51:45AM +0200, Ingo Molnar wrote: > the smp_processor_id()/(HZ*num_cpus) 'interleaving' of every APIC clock > was an SMP scalability issue, and it was done as part of the smptimers > patch. It just got into the kernel much earlier. > > but these days, with the removal of BHs, it might be less of a factor, > mainly because timers have no global synchronization anymore, so we can > again try to not interleave the APIC clocks. Only testing will tell, > because there might be some interaction between timer-generated code > still.
Yes, with earlier versions of smptimers where global_bh_lock was still being acquired to serialize with BHs, local timer clocks needed to be spaced over a HZ to reduce contention. Archs that didn't space the clocks perfromed poorly with smptimers as Anton found out with ppc64 and had to change.
> > Dipankar, wli, would it be possible to try the attached simple patch with > some of the more complex networking loads? The patch gets rid of the APIC > timer interleaving.
I will give it a spin.
Thanks -- Dipankar Sarma <dipankar@in.ibm.com> http://lse.sourceforge.net Linux Technology Center, IBM Software Lab, Bangalore, India. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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