Re: NetBSD truss(1), coredumper(1) and performance bottlenecks

[David Holland <dholland-tech%netbsd.org@localhost>]

On Sat, May 25, 2019 at 09:19:39AM +0700, Robert Elz wrote:
 >   | My observation was general that this syscall is frequently called by
 >   | many programs. Optimization of it can potentially change responsiveness
 >   | of the whole system.
 > 
 > Yes, gettimeofday() is very common - but we need to investigate how
 > to speed it up, not just presume that a mapped page is the right answer.
 > 
 > Using a mapped page would mean processes would only see the time as it was
 > last updated in the kernel -

That obviously sucks :-)  The general mapped page scheme is that the
processor has some kind of usermode-accessible tick counter or timer
and the mapped page contains the offset and/or scale needed to convert
that to a useful time. On old processors without such a widget, it
basically doesn't work.

 > I am sure there are, but I very much doubt that build.sh is really something
 > itself that ought to be a target of investigation.   All it is is a wrapper
 > around make.   All the real work is done in make, and all that it calls.
 > Speeding up build.sh itself is very unlikely to change anything, unless we
 > can find entire runs of make that we can optimise away.

make is very slow :-|

-- 
David A. Holland
dholland%netbsd.org@localhost