Messages in this thread | | | Date | Fri, 7 Feb 2014 09:24:37 +0100 | From | Torsten Duwe <> | Subject | Re: [PATCH] Convert powerpc simple spinlocks into ticket locks |
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On Thu, Feb 06, 2014 at 07:08:26PM +0100, Peter Zijlstra wrote: > On Thu, Feb 06, 2014 at 06:37:27PM +0100, Torsten Duwe wrote: > > I must admit that I haven't tested the patch on non-pseries ppc64 nor on > > ppc32. Only ppc64 has the ldarx and I tried to atomically replace the > > holder along with the locks. That might prove unneccessary. > > But what is the holder for? Can't we do away with that field?
Scott, Peter: good questions. The conditional is wrong because I confused pSeries with ppc64 CPUs with 64-bit kernels. I got deluded by the LOCK_TOKEN definition above. Is that correctly ifdef'd, with PPC64? The holder field should be ifdef'd CONFIG_PPC_SPLPAR, independent of ppc64.
It is an advisory performance hint, and doesn't need to be updated atomically with the lock; this and the above are 2 reasons to drop the asm string operand size voodoo as well.
Thanks, Torsten
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