Viesturs Lācis wrote: > 2011/4/1<[email protected]>: > >> The isolcpus parameter used to be a mask, but now it's a list (there are >> things called "cpusets" now as well, which are way cool but unused by us). >> You could isolate cores 1 and 3 with "isolcpus=1,3". >> >> All that isolcpus does is to tell the Linux scheduler to not schedule any >> process on that CPU/core unless the process specifically requests to be >> put there. >> > And how does EMC happen to get access to that isolated core? > The RTAI/RTAPI layer, which is a shim between EMC/HAL and the underlying RTAI realtime system, explicitly asks to run on the highest numbered processor. > According to Your argument, there must be some code, which requests that. > I did the "isolcpus" tweak and disabled hyperthreading on D525 board, > but I do not recall changing anything with EMC, so my conclusion is > that EMC does that by default. Is that correct? > Correct. Note that one of the wiki pages that mentions isolcpus says that you should set isolcpus=2,3 if you have hyperthreading enabled. If you don't, then the physical core that runs the EMC code may also be running non-realtime code simultaneously, which probably isn't what you want.
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