On Fri, 2023-10-20 at 14:43 +0200, Benjamin Beichler wrote: > > > Yes but you need to schedule for the interrupt, and you don't > > > necessarily know what 'current time' is at interrupt time. > > > > > > So let's say you have "something" that's scheduled to run at times > > > - 1000 > > > - 2000 > > > - 3000 > > > > > > and free-until is 10000 or something high. > > > > > It can also happen without free-until, then it just depends which one of > > the two - they're running in parallel now (linux doing time-travel > > interrupt handling and adding the event, the other thing continuing to > > schedule and doing the next entry) - asks the controller first. > > Since they happen at the same time, most discrete event simulations make > the assumption, that the actual order of execution should not be part of > the semantics. >
Well, fair, but they can bounce more messages around them, and that should change things. I don't think we've built a simulation system here that can strictly assume this is true. In any case, it can get worse - if he sender process actually updated the controller to 2000 by the time the linux actually calls time_travel_add_irq_event(), the linux event will run at 2000 instead of 1000. All this is why we have the vhost-user extensions for ACK messages etc. johannes _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um
