Author: neel
Date: Wed Jan 9 02:11:16 2013
New Revision: 245204
URL: http://svnweb.freebsd.org/changeset/base/245204
Log:
Add a "pause" to busy wait loops in the cpu reset path.
This should not matter much when running on bare metal but it makes the guest
more friendly when running inside a virtual machine.
Discussed with: jhb
Obtained from: NetApp
Modified:
head/sys/amd64/amd64/vm_machdep.c
Modified: head/sys/amd64/amd64/vm_machdep.c
==============================================================================
--- head/sys/amd64/amd64/vm_machdep.c Wed Jan 9 01:54:17 2013
(r245203)
+++ head/sys/amd64/amd64/vm_machdep.c Wed Jan 9 02:11:16 2013
(r245204)
@@ -575,7 +575,8 @@ cpu_reset_proxy()
cpu_reset_proxy_active = 1;
while (cpu_reset_proxy_active == 1)
- ; /* Wait for other cpu to see that we've started */
+ ia32_pause(); /* Wait for other cpu to see that we've started */
+
CPU_SETOF(cpu_reset_proxyid, &tcrp);
stop_cpus(tcrp);
printf("cpu_reset_proxy: Stopped CPU %d\n", cpu_reset_proxyid);
@@ -611,14 +612,17 @@ cpu_reset()
wmb();
cnt = 0;
- while (cpu_reset_proxy_active == 0 && cnt < 10000000)
+ while (cpu_reset_proxy_active == 0 && cnt < 10000000) {
+ ia32_pause();
cnt++; /* Wait for BSP to announce restart */
+ }
if (cpu_reset_proxy_active == 0)
printf("cpu_reset: Failed to restart BSP\n");
enable_intr();
cpu_reset_proxy_active = 2;
- while (1);
+ while (1)
+ ia32_pause();
/* NOTREACHED */
}
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