Messages in this thread | | | Subject | Re: [PATCH] Convert powerpc simple spinlocks into ticket locks | From | Benjamin Herrenschmidt <> | Date | Mon, 10 Feb 2014 14:05:26 +1100 |
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On Fri, 2014-02-07 at 09:51 -0600, Kumar Gala wrote: > On Feb 7, 2014, at 3:02 AM, Torsten Duwe <duwe@lst.de> wrote: > > > On Thu, Feb 06, 2014 at 02:19:52PM -0600, Scott Wood wrote: > >> On Thu, 2014-02-06 at 18:37 +0100, Torsten Duwe wrote: > >>> On Thu, Feb 06, 2014 at 05:38:37PM +0100, Peter Zijlstra wrote: > >> > >>>> Can you pair lwarx with sthcx ? I couldn't immediately find the answer > >>>> in the PowerISA doc. If so I think you can do better by being able to > >>>> atomically load both tickets but only storing the head without affecting > >>>> the tail. > > > > Can I simply write the half word, without a reservation, or will the HW caches > > mess up the other half? Will it ruin the cache coherency on some (sub)architectures? > > The coherency should be fine, I just can’t remember if you’ll lose the reservation by doing this.
Yes you do.
> >> Plus, sthcx doesn't exist on all PPC chips. > > > > Which ones are lacking it? Do all have at least a simple 16-bit store? > > Everything implements a simple 16-bit store, just not everything implements the store conditional of 16-bit data.
Ben.
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