[src/trunk]: src/sys/rump/net/lib/libshmif introduce a sleep to trying to gra...

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

details:   https://anonhg.NetBSD.org/src/rev/ecd13f84221b
branches:  trunk
changeset: 757120:ecd13f84221b
user:      pooka <pooka%NetBSD.org@localhost>
date:      Sun Aug 15 18:47:38 2010 +0000

description:
introduce a sleep to trying to grab the bus

diffstat:

 sys/rump/net/lib/libshmif/shmif_busops.c |  20 ++++++++++++++++----
 1 files changed, 16 insertions(+), 4 deletions(-)

diffs (50 lines):

diff -r 6c32c66781fe -r ecd13f84221b sys/rump/net/lib/libshmif/shmif_busops.c
--- a/sys/rump/net/lib/libshmif/shmif_busops.c  Sun Aug 15 18:40:41 2010 +0000
+++ b/sys/rump/net/lib/libshmif/shmif_busops.c  Sun Aug 15 18:47:38 2010 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: shmif_busops.c,v 1.2 2010/08/13 10:13:44 pooka Exp $   */
+/*     $NetBSD: shmif_busops.c,v 1.3 2010/08/15 18:47:38 pooka Exp $   */
 
 /*
  * Copyright (c) 2009 Antti Kantee.  All Rights Reserved.
@@ -28,7 +28,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: shmif_busops.c,v 1.2 2010/08/13 10:13:44 pooka Exp $");
+__KERNEL_RCSID(0, "$NetBSD: shmif_busops.c,v 1.3 2010/08/15 18:47:38 pooka Exp $");
 
 #include <sys/param.h>
 #include <sys/atomic.h>
@@ -44,6 +44,7 @@
 
 #define LOCK_UNLOCKED  0
 #define LOCK_LOCKED    1
+#define LOCK_COOLDOWN  1001
 
 /*
  * This locking needs work and will misbehave severely if:
@@ -53,10 +54,21 @@
 void
 shmif_lockbus(struct shmif_mem *busmem)
 {
+       int i = 0;
 
-       while (atomic_cas_32(&busmem->shm_lock,
-           LOCK_UNLOCKED, LOCK_LOCKED) == LOCK_LOCKED)
+       while (__predict_false(atomic_cas_32(&busmem->shm_lock,
+           LOCK_UNLOCKED, LOCK_LOCKED) == LOCK_LOCKED)) {
+               if (__predict_false(++i > LOCK_COOLDOWN)) {
+                       uint64_t sec, nsec;
+                       int error;
+
+                       sec = 0;
+                       nsec = 1000*1000; /* 1ms */
+                       rumpuser_nanosleep(&sec, &nsec, &error);
+                       i = 0;
+               }
                continue;
+       }
        membar_enter();
 }