14 Jan
2010
14 Jan
'10
1:49 p.m.
On Thu, Jan 14, 2010 at 11:41:26AM +0100, Philipp ??berbacher wrote:
Excerpts from Ken Restivo's message of Thu Jan 14
02:38:04 +0100 2010:
What are your JACK period settings? Is it less than 64? Mine are
-R -P70 -dalsa -X seq -r48000 -p128 -n3 -Phw:1,0 -Chw:1,1
Fons' code is like a finely-crafted jewel, and it is written in a terse style that
looks to me like hand-optimised ASM code (i.e., variable names that are more like register
names: "_s1", "gy", "dx"), but I'm starting to
understand it a little bit.
It looks like he's windowing through the frames, and if the frame is > 80 bytes, he
windows through it in 64-byte increments. I am using 3 periods of 128bytes each.
-ken
I've been running Fons's great Auto-Wah
on my 32-bit Netbook for many months
now, using it live constantly, and I love it.
I'm going into the studio Friday, so I've dusted off my 64-bit Core 2 Duo
system and putting it through its paces.
Turns out that on my Core2Duo, JACK RACK running Fons's auto-wah plugin sucks
up 6% CPU even if there is no sound going through it.
I asked Fons about it; he can't duplicate the problem since he doesn't have a
64-bit system. Hell, I can't even duplicate it on my 32-bit system; it's 64-bit
dependent.
I looked at the output with Bitmeter at Fons' suggestion, and it seems there
are no denormals, inf's, or nans-- just a very small -230dB DC offset in the
code (probably to avoid denormals).
The CPU usage ramps up before any signal is fed into the plugin. It runs
normally when there is signal, but then it keeps sucking up CPU afterwards. I'm
feeding it from fluidsynth, and bitmeter says that it isn't sending anthing at
all during silent moments.
It doesn't run away to 99% CPU (or 50% on a Core2Duo), like it would if there
were a denormal. But still, why is it using up CPU when there's no signal? That
seems odd. And why only on my 64-bit machine? FWIW, the 64-bit and 32-bit
machines I have are even running the same kernel and RT-patch versions
(2.6.26.8-rt12).
Can someone with a 64-bit system help me by trying to duplicate the problem?
I'm looking to see if JACK-RACK running just Fons' plugin uses as much CPU with
silence as when there's signal running through it.
Oh, and in case it's setting-dependent, here is the rack with the settings I'm
using:
http://restivo.org/misc/clavy-phaser.rack
-ken
Hi Ken.
I'm on 64 bit, so I thought I give it a shot, however, my 64 bit system
is a bit unusual since it's only a single core celeron.
The result is vastly different from yours, cpu usage of jack-rack in
htop is 0.0% most of the time, occasionally it shows 1.0%, so not even
when running it shows the 6% you get.
I only give it some webradio from mplayer, and it doesn't seem to matter
whether it's playing or not or whether it's connected, it's all the
same. I was clever enough to enable the plugin in jack-rack.
What I do get around 6% is mem usage (out of 1GB).