Messages in this thread | | | Subject | Re: preempt-rt, NUMA and strange latency traces | From | Sébastien Dugué <> | Date | Fri, 10 Feb 2006 14:18:54 +0100 |
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On Thu, 2006-02-09 at 15:02 -0500, Lee Revell wrote: > On Thu, 2006-02-09 at 12:24 +0100, Sébastien Dugué wrote: > > On Thu, 2006-02-09 at 01:04 -0500, Lee Revell wrote: > > > On Wed, 2006-02-08 at 11:45 +0100, Sébastien Dugué wrote: > > > > The more I think about it, the more I tend to believe it's hardware > > > > related. It seems as if the CPU just hangs for ~27 ms before > > > > resuming processing. > > > > > > That would be an exceptionally long latency - you would probably notice > > > it if the mouse froze, VOIP dropped out, ping stops, etc for 30ms. > > > > > > > It's a test machine and I use it remotely with console redirected so > > no mouse, no RT applications aside from my silly nanosleep() loop. But > > I do notice that that test sometimes takes more time (ie when I get > > those weird latencies). > > Argh. You would think the vendors would consider a 30ms delay > unacceptable. This is big enough to show up on an MRTG graph of ping > times ferchrissake. > > I guess the assumption is that most hardware will never be used for even > soft RT work... > > Lee >
That may be but in that case I may be pushing it a bit far testing that kind of box with realtime stuff.
As a former hw designer I find it useful to have some hardware monitoring capabilities on a system but it should either not be so intrusive or at least we should be able to disable it.
Sébastien.
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