[PATCH 5 of 5] sshpeer: run the ssh command unbuffered

[Matt Mackall]

On Wed, 2015-05-27 at 15:43 -0400, Augie Fackler wrote:
> On Fri, May 22, 2015 at 12:37 PM, Matt Mackall <mpm at selenic.com> wrote:
> > I'm going to wait on this one until we've researched whether it
> > regresses OS X. I've queued the rest for default, thanks.
> 
> 
> What in particular are you worried about on OS X? I can try and run some tests.

The 5x performance regression mentioned in commit cited in the patch.
Basically, at some point we were reading from ssh a byte at a time
according to dtrace... and context switching each time.

This actually will probably be less visible today as Macs are all
multicore and thus can more efficiently slowly dribble data over a pipe
between two processes, but it will probably still manifest as
significantly higher CPU usage.

-- 
Mathematics is the supreme nostalgia of our time.