26 Jul
2009
26 Jul
'09
11:54 p.m.
On Sun, 26 Jul 2009, Brent Busby wrote:
On Sun, 26 Jul 2009, Ken Restivo wrote:
Oddly (and I don't really understand this), you can have *both*. I've seen
recommendations online from people who claim to have gotten good results with
Jack even on laptops by having NO_HZ and HZ_1000 selected. I don't really
know what the effect of this is. Does this mean you generate no ticks except
when you need them, but when you do, the jiffy rate is 1000Hz? This naively
seems to me like a better idea than just running a clock all the time, but I
don't know how that pans out for recording and MIDI.
Ahh. This explains why I've had good results with NO_HZ for the
last year. I have both NO_HZ and HZ_1000 enabled. I still don't
understand how these two interact. At the very least, this would
provide the fallback for booting the kernel with nohz=off.
I've
also run into a handful of config options that either help or hurt
realtime performance, depending on the specific hardware:
NO_HZ (seems to work properly on most hardware these days)
Is that advised? I was told to use HZ_1000 in order to get MIDI to work
correctly. Should I be using NO_HZ instead? I've got several machines to
configure: a 32-bit Atom EEE, a 64-bit Intel Micro-ITX, and a 64-bit Asus
Intel Core2Duo It seems like there ought to be more pooling of
resources regarding complete
kernel configs that work. Everyone always talks about the patches
themselves...but anyone who can do 'patch -p1' against a tree of source code
can get that part right.
--
+ Brent A. Busby + "We've all heard that a million monkeys
+ UNIX Systems Admin + banging on a million typewriters will
+ University of Chicago + eventually reproduce the entire works of
+ Physical Sciences Div. + Shakespeare. Now, thanks to the Internet,
+ James Franck Institute + we know this is not true." -Robert Wilensky
I'm willing to post my config for the AMD laptop once I get the
right combination of HZ, RTC, and HPET options set. I'm still
running Fedora 8 on my Core2Quad, so I've stopped at 2.6.24.7-rt27
with everything running perfectly, but I can post the config from
that box if anyone is interested.
Cheers,
--ww