Lots and lots of system time

Harald Hanche-Olsen hanche at math.ntnu.no
Sat Nov 26 02:53:36 PST 2011

[Brandon Allbery <allbery.b at gmail.com> (2011-11-25 20:50:21 UTC)]

> On Fri, Nov 25, 2011 at 15:08, Harald Hanche-Olsen <hanche at math.ntnu.no>wrote:
> > I have no idea what mach_kernel`chud is or does, but it disappears from
> > the list when the compilation is stopped. (So do the dtrace functions,
> > BTW.) The script runs for ten seconds, so
> CHUD is part of the instrumentation, I think (Computer Hardware
> Understanding for Developers; if it hasn't been folded into DTrace then it
> is at least *used* by DTrace).

Aha. Thanks; I'll ignore chud then.

> You may want to look for "Instruments", which is part of XCode and
> makes using DTrace to figure out what a process is doing much
> easier.

Again thanks. But something is wrong, either with my setup or my
understanding, for I am unable to make Instruments display any
information. Also, "Instruments help" doesn't bring up any window.

Uh, sorry about going off topic ... I'll ask elsewhere if I can't
figure it out on my own.

> In any case, I would be interested to see what happens if you turn off
> multiple jobs.  I wouldn't necessarily assume that psynch_cvwait doesn't
> use CPU, by the way; busywaiting is often used for what are expected to be
> short delays waiting on a mutex.  ("port install ... build.njobs=1", IIRC)

Trying that now, it didn't make any difference. Where could I found
out about options such as build.njobs, BTW? I looked around to verify
that you did RC, but to no avail.

- Harald

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