PERFORCE change 93943 for review
John Baldwin
jhb at FreeBSD.org
Fri Mar 24 19:58:01 UTC 2006
http://perforce.freebsd.org/chv.cgi?CH=93943
Change 93943 by jhb at jhb_slimer on 2006/03/24 19:57:35
Force the TD_IS_RUNNING check in the adaptive spin to treat
td_state as volatile. On amd64 the compiler was caching the
value of td_state in a register. :(
Affected files ...
.. //depot/projects/smpng/sys/kern/kern_mutex.c#119 edit
.. //depot/projects/smpng/sys/sys/proc.h#167 edit
Differences ...
==== //depot/projects/smpng/sys/kern/kern_mutex.c#119 (text+ko) ====
@@ -551,8 +551,14 @@
if (m != &Giant && TD_IS_RUNNING(owner)) {
#endif
turnstile_release(&m->mtx_object);
+
+ /*
+ * Inline expansion of TD_IS_RUNNING(owner) to
+ * force volatile.
+ */
while (mtx_rawowner(m) == owner &&
- TD_IS_RUNNING(owner)) {
+ (volatile enum _td_state)owner->td_state ==
+ TDS_RUNNING) {
cpu_spinwait();
}
continue;
==== //depot/projects/smpng/sys/sys/proc.h#167 (text+ko) ====
@@ -311,7 +311,7 @@
* or already have been set in the allocator, constructor, etc.
*/
struct pcb *td_pcb; /* (k) Kernel VA of pcb and kstack. */
- enum {
+ enum _td_state {
TDS_INACTIVE = 0x0,
TDS_INHIBITED,
TDS_CAN_RUN,
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