- Run sched_userret() after thread_userret(). Before, sched_userret() would

   lower the priority of the returning thread to a user priority before
   calling into thread_userret() which would call wakeup() which in turn would
   cause the returning thread to eventually context switch rather than
   completing its slice.  Allowing this thread to complete its slice first
   yields a 15% performance improvement in super-smack on my dual opteron with
   4BSD.

1 files changed, 4 insertions, 5 deletions

diff --git a/sys/kern/subr_trap.c b/sys/kern/subr_trap.c
index 89fab49..96261e9 100644
--- a/sys/kern/subr_trap.c
+++ b/sys/kern/subr_trap.c
@@ -102,11 +102,6 @@ userret(td, frame, oticks)
 		g_waitidle();
 
 	/*
-	 * Let the scheduler adjust our priority etc.
-	 */
-	sched_userret(td);
-
-	/*
 	 * We need to check to see if we have to exit or wait due to a
 	 * single threading requirement or some other STOP condition.
 	 * Don't bother doing all the work if the stop bits are not set
@@ -133,6 +128,10 @@ userret(td, frame, oticks)
 		ticks = td->td_sticks - oticks;
 		addupc_task(td, TRAPF_PC(frame), (u_int)ticks * psratio);
 	}
+	/*
+	 * Let the scheduler adjust our priority etc.
+	 */
+	sched_userret(td);
 }
 
 /*