26 Mar
2013
26 Mar
'13
10:25 a.m.
On 03/25/2013 01:15 PM, Len Ovens wrote:
On Mon, March 25, 2013 1:39 pm, Jostein Chr. Andersen wrote:
Thanks! Now I'm curious why a BIOS can't turn off HT ...
--
David
gnome(a)hawaii.rr.com
authenticity, honesty, community
http://clanjones.org/david/
http://dancing-treefrog.deviantart.com/
On 03/25/2013 08:06 PM, david wrote:
That should be all you need with two cores, turn off cpu 0 and 2, though
most people turn off 1 and 3 :)
The laptop I'm considering (Zareason Verix
530) as replacement for my
current one has a dual-core Intel i3 processor with hyperthreading.
Zareason says there's no way to turn off HT in BIOS.
I think folk on the list have said that HT causes problems with RT. So
how can I disable hyperthreading?
I can do like this in my Kubuntu system which have 8 kernels:
sudo echo 0 > /sys/devices/system/node/node0/cpu0/online
sudo echo 0 > /sys/devices/system/node/node0/cpu2/online sudo echo 0 >
/sys/devices/system/node/node0/cpu7/online
Which is why the cpu 7 here.
Linux sees the each core as two cpus, one for each thread. Not only might
a thread be using too much time but there is also the overhead of context
switching (invisible to the kernel) from one thread to the other. With
hyper threading on, I can run jack at 64 frames with few xruns. With
hyperthreading off, I can get down to 16 frames with guitarix running and
no xruns. (10 year old single core p4 at 2.4G) Read up on some of the cnc
projects where they require lower latency than audio. Lots of good info.