Integrate preemption state machine with Linux scheduler

Track when a processor is going to schedule "soon".

1 files changed, 6 insertions, 0 deletions

diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index 7ce9fb210d55..431c3d29a667 100644
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -24,6 +24,7 @@
 #include <linux/cpu.h>
 #include <linux/gfp.h>
 
+#include <litmus/preempt.h>
 #include <litmus/debug_trace.h>
 
 #include <asm/mtrr.h>
@@ -275,6 +276,11 @@ __visible void smp_reschedule_interrupt(struct pt_regs *regs)
         /*
          * KVM uses this interrupt to force a cpu out of guest mode
          */
+
+        /* LITMUS^RT: this IPI might need to trigger the sched state machine.
+         * Starting from 3.0 schedule_ipi() actually does something.  This may
+         * increase IPI latencies compared with previous versions. */
+        sched_state_ipi();
 }
 
 static inline void smp_entering_irq(void)