Gilles, Thanks for responding. I had also checked what you describe. Unfortunately it is the ACPI interrupt that causes the delay and is also responsible for keeping the motherboard powered.
It's not the first time I hit the SMI induced latency problem, but it is the first board that goes as far as to actually reset itself. Jeroen. 2013/4/9 Gilles Chanteperdrix <[email protected]> > On 03/13/2013 08:43 PM, Jeroen Van den Keybus wrote: > > > Hi, > > > > > > We have configured Linux 3.5.7 / Xenomai 2.6.2.1 on an MSI-7514 mainboard > > with a Core 2 Duo CPU. > > > > This configuration suffers from excessive worst-case latencies during the > > 'latency' test (on average: 2.6 µs, worst-case around 1900 µs, around 10 > > overruns per second). I believe these overruns are due to the CPUs > entering > > SM mode (SMI). As soon as the ACPI BIOS SMI is disabled (when > > xeno_nucleus/native are loaded as a module), the computer shuts down in 5 > > secs. or so. Presumably some power supply watchdog on the mainboard isn't > > triggered. > > > > - Has someone also observed this behaviour and maybe solved it in some > way ? > > - I looked around in the Intel manuals and I don't think it's possible to > > have only 1 CPU handle these SMIs. Is that correct ? If it were possible, > > we could run RT tasks on the other one, obviously, but currently latency > > shows overruns on both CPUs. > > - Would it somehow be possible/sensible to leave the SMI disabled and > > generically call the SMI handler directly from within (a task in) the OS > ? > > There's probably going to be issues, the least of which would be proper > > handling of the RSM instruction outside SM mode. But still... > > > Hi, > > I see this post has not received an answer after a long time. What can > be done for sure is only disabling some sources of SMI, the SMI > workaround module tries to do that, but probably has not a knob for > every possible SMI source. So, what you should do is get the datasheet > for the precise Intel ICH you own, and try and find all the SMI sources. > Then try and find which one causes the latency issues, with the hope > that it is not also the one needed to avoid the reboot. > > Regards. > > -- > Gilles. > > _______________________________________________ Xenomai mailing list [email protected] http://www.xenomai.org/mailman/listinfo/xenomai
