On Wed, Nov 27, 2013 at 02:40:04PM -0800, H. Peter Anvin wrote: > Also don't forget we need the IPIs, too...
Yeah, I was simply looking at whether we could get away with executing an empty syscall, i.e. save us the CPUID and rely only on the IPIs and IRET. But we don't IPI ourselves in smp_call_function; actually we remove ourselves from the cpumask because of deadlocking scenarios. So on this_cpu we only execute the function with IRQs disabled and CLI/STI is not serializing. I wonder if we could use MFENCE instead of CPUID, though, and save us the clobbering of e*x, maybe even save us some cycles since MFENCE should be faster than hundred-ish cycles of microcoded CPUID. :-) -- Regards/Gruss, Boris. Sent from a fat crate under my desk. Formatting is fine. -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/