[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v9 05/19] qspinlock: Optimize for smaller NR_CPUS
On 04/17/2014 11:51 AM, Peter Zijlstra wrote: On Thu, Apr 17, 2014 at 11:03:57AM -0400, Waiman Long wrote:@@ -48,6 +53,9 @@ * We can further change the first spinner to spin on a bit in the lock word * instead of its node; whereby avoiding the need to carry a node from lock to * unlock, and preserving API. + * + * N.B. The current implementation only supports architectures that allow + * atomic operations on smaller 8-bit and 16-bit data types. */Only for the _Q_PENDING_BITS == 8 case, the other case should still be fine. Yes, but _Q_PENDING_BITS is controlled by NR_CPUS which, for almost all the distributions, is less than 16K which means _Q_PENDING_BITS will always be set to 8, especially for non-x86 architectures. -Longman _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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