[src/trunk]: src/sys/kern - use scaled calculations for avgcount

[yamt <yamt%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/3163d2aa5d67
branches:  trunk
changeset: 785252:3163d2aa5d67
user:      yamt <yamt%NetBSD.org@localhost>
date:      Wed Mar 06 11:25:01 2013 +0000

description:
- use scaled calculations for avgcount
- sched_balance: account lwp which is currently running
- sched_balance: skip cpus w/o migratable lwps

diffstat:

 sys/kern/kern_runq.c |  20 ++++++++++++++++----
 1 files changed, 16 insertions(+), 4 deletions(-)

diffs (58 lines):

diff -r cbc5227ce2ea -r 3163d2aa5d67 sys/kern/kern_runq.c
--- a/sys/kern/kern_runq.c      Wed Mar 06 11:20:10 2013 +0000
+++ b/sys/kern/kern_runq.c      Wed Mar 06 11:25:01 2013 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_runq.c,v 1.36 2013/02/09 00:31:21 christos Exp $  */
+/*     $NetBSD: kern_runq.c,v 1.37 2013/03/06 11:25:01 yamt Exp $      */
 
 /*
  * Copyright (c) 2007, 2008 Mindaugas Rasiukevicius <rmind at NetBSD org>
@@ -27,7 +27,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_runq.c,v 1.36 2013/02/09 00:31:21 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_runq.c,v 1.37 2013/03/06 11:25:01 yamt Exp $");
 
 #include <sys/param.h>
 #include <sys/kernel.h>
@@ -90,6 +90,8 @@
        struct evcnt    r_ev_localize;
 } runqueue_t;
 
+#define        AVGCOUNT_SHIFT  4       /* shift for r_avgcount */
+
 static void *  sched_getrq(runqueue_t *, const pri_t);
 #ifdef MULTIPROCESSOR
 static lwp_t * sched_catchlwp(struct cpu_info *);
@@ -383,7 +385,7 @@
        /* Make sure that thread is in appropriate processor-set */
        if (__predict_true(spc->spc_psid == l->l_psid)) {
                /* If CPU of this thread is idling - run there */
-               if (ci_rq->r_count == 0) {
+               if (ci_rq->r_avgcount <= (1 << AVGCOUNT_SHIFT)) {
                        ci_rq->r_ev_stay.ev_count++;
                        return ci;
                }
@@ -522,10 +524,20 @@
 
        /* Make lockless countings */
        for (CPU_INFO_FOREACH(cii, ci)) {
+               const bool notidle = ci->ci_data.cpu_idlelwp != ci->ci_curlwp;
+               u_int nrunning;
+
                ci_rq = ci->ci_schedstate.spc_sched_info;
 
                /* Average count of the threads */
-               ci_rq->r_avgcount = (ci_rq->r_avgcount + ci_rq->r_mcount) >> 1;
+               nrunning = ci_rq->r_count + notidle;
+               ci_rq->r_avgcount = (ci_rq->r_avgcount +
+                   (nrunning << AVGCOUNT_SHIFT)) >> 1;
+
+               /* We are not interested in a CPU without migratable threads */
+               if (ci_rq->r_mcount == 0) {
+                       continue;
+               }
 
                /* Look for CPU with the highest average */
                if (ci_rq->r_avgcount > highest) {