Latency Tuning Questions
I've been trying some of the tips found in this older wikki'
I'm currently trying;
GRUB_CMDLINE_LINUX_DEFAULT="isolcpus=1 intel_idle.max_cstate=0 processor.max_cstate=0 idle=poll"
The wiki says not to permanently run all these combined settings as the CPU can over heat.
Are these still valid settings for Preempt_RT and Stretch? Are there different settings for Stretch?
The changes helped somewhat. When I run latency test by itself I get the following;
Servo 2K ns
Base 7K ns
Which is much better. When I open the Browser run a utube video they jump to 90-130K which is only slightly better then without the changes. If I bang around, like writing this post they climb to 195K, 140K ns respectively.
Todd Zuercher wrote: The little I've played with a Peempt-rt machine, this is what I found. Turn off all power management and Core2Duos states in the Bios, have at least 2gb of memory, and try isolcpus. Isolcpus made a pretty big difference on the i5 cpu machine I was messing with. I don't think the cpu hog and idle poll techniques are applicable to Preemt-RT (or were even a good idea when they were. )
PS I forgot to say, don't forget to turn off Hyperthreading in the BIOS, it is utterly useless for real time.
If you replace the E2180 with a E8500 you get about double the performance and
3 times the cache size (for about 6 bucks on Ebay)...
Edit: Note if you intend to use a Ethernet card you should not have a base thread enabled
in your test as it will give inaccurate results.
Heres a E8500 Core Duo on a HP DC7800, with a current kernel
(3 day test doing normal browsing + GLXGears)
More about fstab and file mounting options.