Hi Tim,

On Mon, Feb 9, 2015 at 5:02 PM, tim Rowledge <tim@rowledge.org> wrote:

On 09-02-2015, at 4:53 PM, Eliot Miranda <eliot.miranda@gmail.com> wrote:
> No.  The heartbeat is extremely cheap.  It is the idle loop that calls ioRelinquishProcessorForMicroseconds which in turn calls aioSleepForUsecs which calls select:

Happy to be shown wrong. That means it most likely is morphic and/or any other tucked away processes. On a Pi it seems to be about 15% cpu time, so there is certainly some interest in reducing it!

it is this one:

"A default background process which is invisible."

[self relinquishProcessorForMicroseconds: 1000] repeat
If you recall the VW VM, that got rid of the background process and when the VM scheduling loop finds nothing to run it calls a blocking routine.