Mailing List Archive

# HG changeset patch
# User Keir Fraser <keir@xen.org>
# Date 1293179464 0
# Node ID df310dcd19cb7b5840a1f73431abb7aa87531122
# Parent 6a970abb346f1767523649240a6307e55dfcd76c
credit2: Migrate request infrastructure

Put in infrastructure to allow a vcpu to requeset to migrate to a
specific runqueue. This will allow a load balancer to choose running
VMs to migrate, and know they will go where expected when the VM is
descheduled.

Signed-off-by: George Dunlap <george.dunlap@eu.citrix.com>
---
xen/common/sched_credit2.c | 38 +++++++++++++++++++++++++++++++++++---
1 files changed, 35 insertions(+), 3 deletions(-)

diff -r 6a970abb346f -r df310dcd19cb xen/common/sched_credit2.c
--- a/xen/common/sched_credit2.c Fri Dec 24 08:30:42 2010 +0000
+++ b/xen/common/sched_credit2.c Fri Dec 24 08:31:04 2010 +0000
@@ -157,6 +157,12 @@
*/
#define __CSFLAG_delayed_runq_add 2
#define CSFLAG_delayed_runq_add (1<<__CSFLAG_delayed_runq_add)
+/* CSFLAG_runq_migrate_request: This vcpu is being migrated as a result of a
+ * credit2-initiated runq migrate request; migrate it to the runqueue indicated
+ * in the svc struct.
+ */
+#define __CSFLAG_runq_migrate_request 3
+#define CSFLAG_runq_migrate_request (1<<__CSFLAG_runq_migrate_request)


int opt_migrate_resist=500;
@@ -247,6 +253,8 @@ struct csched_vcpu {
/* Individual contribution to load */
s_time_t load_last_update; /* Last time average was updated */
s_time_t avgload; /* Decaying queue load */
+
+ struct csched_runqueue_data *migrate_rqd; /* Pre-determined rqd to which to migrate */
};

/*
@@ -974,10 +982,10 @@ csched_context_saved(const struct schedu
* it seems a bit pointless; especially as we have plenty of
* bits free.
*/
- if ( test_bit(__CSFLAG_delayed_runq_add, &svc->flags) )
+ if ( test_and_clear_bit(__CSFLAG_delayed_runq_add, &svc->flags)
+ && likely(vcpu_runnable(vc)) )
{
BUG_ON(__vcpu_on_runq(svc));
- clear_bit(__CSFLAG_delayed_runq_add, &svc->flags);

runq_insert(ops, vc->processor, svc);
runq_tickle(ops, vc->processor, svc, now);
@@ -1015,9 +1023,32 @@ choose_cpu(const struct scheduler *ops,

if ( !spin_trylock(&prv->lock) )
{
+ if ( test_and_clear_bit(__CSFLAG_runq_migrate_request, &svc->flags) )
+ {
+ d2printk("d%dv%d -\n", svc->vcpu->domain->domain_id, svc->vcpu->vcpu_id);
+ clear_bit(__CSFLAG_runq_migrate_request, &svc->flags);
+ }
/* Leave it where it is for now. When we actually pay attention
* to affinity we'll have to figure something out... */
return vc->processor;
+ }
+
+ /* First check to see if we're here because someone else suggested a place
+ * for us to move. */
+ if ( test_and_clear_bit(__CSFLAG_runq_migrate_request, &svc->flags) )
+ {
+ if ( unlikely(svc->migrate_rqd->id < 0) )
+ {
+ printk("%s: Runqueue migrate aborted because target runqueue disappeared!\n",
+ __func__);
+ /* Fall-through to normal cpu pick */
+ }
+ else
+ {
+ d2printk("d%dv%d +\n", svc->vcpu->domain->domain_id, svc->vcpu->vcpu_id);
+ new_cpu = first_cpu(svc->migrate_rqd->active);
+ goto out_up;
+ }
}

/* FIXME: Pay attention to cpu affinity */
@@ -1053,7 +1084,8 @@ choose_cpu(const struct scheduler *ops,
BUG_ON(cpus_empty(prv->rqd[min_rqi].active));
new_cpu = first_cpu(prv->rqd[min_rqi].active);
}
-
+
+out_up:
spin_unlock(&prv->lock);

return new_cpu;

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