https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=264867
Mark Johnston <[email protected]> changed: What |Removed |Added ---------------------------------------------------------------------------- Assignee|[email protected] |[email protected] --- Comment #16 from Mark Johnston <[email protected]> --- Ok, I'm still able to reproduce the problem with my patch. But, the frequency of the late wakeups is much much lower, and I'm fairly sure that the patch solves a legitimate problem on its own. Specifically, getnextcpuevent() contains the following bit of code: /* Handle callout events. */ if (event > state->nextcall) event = state->nextcall; It gets called when a CPU goes idle, and the idle thread is scheduling the next timer interrupt. "nextcall" is not volatile, and interrupts are enabled, so state->nextcall can be modified between the check and the load, and the CPU will end up using a stale value. It might be that there is another, similar race in handleevents(), since a different CPU might be updating state->nextcall concurrently. But I think the race is harmless since callout_process() should be able to find the next callout... -- You are receiving this mail because: You are the assignee for the bug.
