Messages in this thread | | | Date | Tue, 28 Apr 2015 18:40:33 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 2/2] [PATCH] sched: Add smp_rmb() in task rq locking cycles |
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On Tue, Apr 28, 2015 at 11:53:21AM -0400, Chris Metcalf wrote:
> The reason we use two 32-bit fields on tilepro is that the only available > atomic instruction is tns (test and set), which sets a 32-bit "1" value > into the target memory and returns the old 32-bit value.
And you want a ticket lock as opposed to the test-and-set lock because with 64 tiles starvation under contention is a real worry?
Where sparc32 (which only has the load-store-unsigned-byte instruction, which is similar to your tns except it writes 0xff) has the benefit of not actually having many CPUs you get to do 64 cpus!
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