On Fri, Mar 13, 2020 at 03:43:40PM +0000, Vincenzo Frascino wrote: > The vDSO library should only include the necessary headers required for > a userspace library (UAPI and a minimal set of kernel headers). To make > this possible it is necessary to isolate from the kernel headers the > common parts that are strictly necessary to build the library. > > Introduce asm/vdso/arch_timer.h to contain all the arm64 specific > code. This allows to replace the second isb() in __arch_get_hw_counter() > with a fake dependent stack read of the counter which improves the vdso > library peformances of ~4.5%. Below the results of vdsotest [1] ran for > 100 iterations. The subject seems to imply a non-functional change but as you read, it gets a lot more complicated. Could you keep the functional change separate from the header clean-up, maybe submit it as an independent patch? And it shouldn't go in without Will's ack ;). -- Catalin
