> * David Laight <[email protected]> wrote: > > > It has already been measured - it is far too slow. > > I don't think proper buffering was tested, was it? Only a per syscall > RDRAND overhead which I can imagine being not too good. >
Well, I have some numbers, but I am struggling to understand one aspect there. So, this is how it looks when PAGE_TABLE_ISOLATION is off: base: Simple syscall: 0.0516 microseconds rdrand (calling every 8 syscalls): Simple syscall: 0.0795 microseconds get_random_bytes (4096 bytes buffer): Simple syscall: 0.0597 microseconds But then it looks like this with PAGE_TABLE_ISOLATION is on: base: Simple syscall: 0.1761 microseconds get_random_bytes (4096 bytes buffer): Simple syscall: 0.1793 microseconds get_random_bytes (64 bytes buffer): Simple syscall: 0.1866 microseconds rdrand (calling every 8 syscalls): Simple syscall: 0.3131 microseconds So, suddenly calling rdrand is much more pricey... Either smth is really weird going on when PAGE_TABLE is enabled, or I managed to do smth wrongly (no idea what although). I will continue Investigating. Best Regards, Elena.
