Re: [RFC][PATCH] powerpc/64s: optimise syscall entry with relon hypercalls

2017-02-13 Thread Nicholas Piggin
On Mon, 13 Feb 2017 11:04:06 + David Laight wrote: > From: Nicholas Piggin > > Sent: 10 February 2017 18:23 > > After bc3551257a ("powerpc/64: Allow for relocation-on interrupts from > > guest to host"), a getppid() system call goes from 307 cycles to 358 > > cycles

RE: [RFC][PATCH] powerpc/64s: optimise syscall entry with relon hypercalls

2017-02-13 Thread David Laight
From: Nicholas Piggin > Sent: 10 February 2017 18:23 > After bc3551257a ("powerpc/64: Allow for relocation-on interrupts from > guest to host"), a getppid() system call goes from 307 cycles to 358 > cycles (+17%). This is due significantly to the scratch SPR used by the > hypercall. > > It turns