On Wed, Apr 13, 2016 at 11:37:21AM -0400, Waiman Long wrote: > The TSC clocksource, on the other hand, is per cpu. So there won't be much > contention in accessing it. Normally TSC will be used the default clock > source. However, if there is too much variation in the actual clock speeds > of the individual CPUs,
Does the system actually have a clock rate skew? Not an offset? > it will cause the TSC calibration to fail and revert > to use hpet as the clock source. During bootup, hpet will usually be > selected as the default clock source first. After a short time, the TSC will > take over as the default clock source. Problem can happen during that short > period of transition time too. In fact, we have 16-socket Broadwell-EX > systems that has this soft lockup problem once in a few reboot cycles which > prompted me to find a solution to fix it. This 16 socket system is a completely broken trainwreck. Trying to use HPET with _that_ many CPUs is absolutely insane. Please tell your hardware engineers to fix the TSC clock domain.
