Yang, Xiaowei wrote:
Tian, Kevin wrote:
From: George Dunlap
Sent: Monday, March 09, 2009 8:56 PM
Hmm, I think this patch may not be exactly what we want. It looks
like it checks for how long a vcpu has been in its current stat, not
how recently it has been running. So if a vcpu sleeps for a long time
on a cpu that's running other workloads, then wakes up
(blocked->runnable), the cache is by no means "hot". But since it has
only been in the "runnable" state for a few hundred cycles, it won't
be migrated, even though there's little cost.
Then to add a per-vcpu last_running_timestamp which is recorded when
vcpu is scheduled out, could hit the purpose here?
Yes, it's more reasonable. I can make a patch.
The patch is attached. Had a quick test using the previous config and
saw no obvious different result with it. May be explained by the fact
that the benchmarks has no many IO operations - db and logfile are put
to ramdisk for sysbench test. Anyway it's closer to what we really want.
Thanks both of you!
Signed-off-by: Xiaowei Yang <xiaowei.yang@xxxxxxxxx>
Thanks,
xiaowei
diff -r 115c97f32dc6 xen/common/sched_credit.c
--- a/xen/common/sched_credit.c Tue Mar 10 00:18:39 2009 +0800
+++ b/xen/common/sched_credit.c Tue Mar 10 03:09:44 2009 +0800
@@ -328,7 +328,7 @@ static inline int
static inline int
__csched_vcpu_is_cache_hot(struct vcpu *v)
{
- int hot = ((NOW() - v->runstate.state_entry_time) <
+ int hot = ((NOW() - v->last_run_time) <
((uint64_t)vcpu_migration_delay * 1000u));
if ( hot )
diff -r 115c97f32dc6 xen/common/schedule.c
--- a/xen/common/schedule.c Tue Mar 10 00:18:39 2009 +0800
+++ b/xen/common/schedule.c Tue Mar 10 03:00:36 2009 +0800
@@ -836,6 +836,7 @@ static void schedule(void)
(test_bit(_VPF_blocked, &prev->pause_flags) ? RUNSTATE_blocked :
(vcpu_runnable(prev) ? RUNSTATE_runnable : RUNSTATE_offline)),
now);
+ prev->last_run_time = now;
ASSERT(next->runstate.state != RUNSTATE_running);
vcpu_runstate_change(next, RUNSTATE_running, now);
diff -r 115c97f32dc6 xen/include/xen/sched.h
--- a/xen/include/xen/sched.h Tue Mar 10 00:18:39 2009 +0800
+++ b/xen/include/xen/sched.h Tue Mar 10 02:59:15 2009 +0800
@@ -102,6 +102,9 @@ struct vcpu
} runstate_guest; /* guest address */
#endif
+ /* last time when vCPU is scheduled out */
+ uint64_t last_run_time;
+
/* Has the FPU been initialised? */
bool_t fpu_initialised;
/* Has the FPU been used since it was last saved? */
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