[LAD] cpu spikes

[Jörn Nettingsmeier]

hi *!


sorry to hijack this thread, but: when enquiring about latency tuning, 
one frequently encounters hints like "disable cron", "disable indexing 
services", "disable this, disable that".

however, none of those alleged culprits run with real-time privileges or 
access driver or kernel code which does. so how can they be a problem 
(and disabling them part of the solution)? i'm asking because i've got 
my own anecdotal evidence that it *does* make a difference...

i understand how device drivers can be nasty (graphics cards locking up 
the pci bus, wifi chips hogging the kernel for milliseconds at a time or 
worse...) but it seems that a) either kernel preemption and real-time 
scheduling is terribly buggy or hand-wavey, or b) we're feeding each 
other snake-oil in recommending to disable userspace things that is 
running without rt privs.

i'd love to be educated on this.


best,


jörn




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Jörn Nettingsmeier
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