On 02/16/2017 11:09 AM, Peter Zijlstra wrote: > On Wed, Feb 15, 2017 at 04:37:49PM -0500, Waiman Long wrote: >> The cpu argument in the function prototype of vcpu_is_preempted() >> is changed from int to long. That makes it easier to provide a better >> optimized assembly version of that function. >> >> For Xen, vcpu_is_preempted(long) calls xen_vcpu_stolen(int), the >> downcast from long to int is not a problem as vCPU number won't exceed >> 32 bits. >> > Note that because of the cast in PVOP_CALL_ARG1() this patch is > pointless. > > Then again, it doesn't seem to affect code generation, so why not. Takes > away the reliance on that weird cast. I add this patch because I am a bit uneasy about clearing the upper 32 bits of rdi and assuming that the compiler won't have a previous use of those bits. It gives me peace of mind. Cheers, Longman
