Mailing List Archive

# HG changeset patch
# User Keir Fraser <keir@xen.org>
# Date 1293179315 0
# Node ID 98f023d7717a1197e2157d5cbdaaced74d703f2a
# Parent d93de09aa9522ae7f603c4ef7b4eaa486cdb7ea4
credit2: Calculate instantaneous runqueue load

Add hooks in the various places to detect vcpus becoming active or
inactive. At the moment, record only instantaneous runqueue load;
but this lays the groundwork for having a load average.

Signed-off-by: George Dunlap <george.dunlap@eu.citrix.com>
---
xen/common/sched_credit2.c | 36 ++++++++++++++++++++++++++++++++++--
1 files changed, 34 insertions(+), 2 deletions(-)

diff -r d93de09aa952 -r 98f023d7717a xen/common/sched_credit2.c
--- a/xen/common/sched_credit2.c Fri Dec 24 08:28:10 2010 +0000
+++ b/xen/common/sched_credit2.c Fri Dec 24 08:28:35 2010 +0000
@@ -42,6 +42,7 @@
#define TRC_CSCHED2_TICKLE TRC_SCHED_CLASS + 6
#define TRC_CSCHED2_CREDIT_RESET TRC_SCHED_CLASS + 7
#define TRC_CSCHED2_SCHED_TASKLET TRC_SCHED_CLASS + 8
+#define TRC_CSCHED2_UPDATE_LOAD TRC_SCHED_CLASS + 9
#define TRC_CSCHED2_RUNQ_ASSIGN TRC_SCHED_CLASS + 10

/*
@@ -187,6 +188,7 @@ struct csched_runqueue_data {

cpumask_t idle, /* Currently idle */
tickled; /* Another cpu in the queue is already targeted for this one */
+ int load; /* Instantaneous load: Length of queue + num non-idle threads */
};

/*
@@ -264,6 +266,23 @@ __runq_elem(struct list_head *elem)
__runq_elem(struct list_head *elem)
{
return list_entry(elem, struct csched_vcpu, runq_elem);
+}
+
+static void
+update_load(const struct scheduler *ops,
+ struct csched_runqueue_data *rqd, int change, s_time_t now)
+{
+ rqd->load += change;
+
+ {
+ struct {
+ unsigned load:4;
+ } d;
+ d.load = rqd->load;
+ trace_var(TRC_CSCHED2_UPDATE_LOAD, 0,
+ sizeof(d),
+ (unsigned char *)&d);
+ }
}

static int
@@ -756,7 +775,11 @@ csched_vcpu_sleep(const struct scheduler
if ( per_cpu(schedule_data, vc->processor).curr == vc )
cpu_raise_softirq(vc->processor, SCHEDULE_SOFTIRQ);
else if ( __vcpu_on_runq(svc) )
+ {
+ BUG_ON(svc->rqd != RQD(ops, vc->processor));
+ update_load(ops, svc->rqd, -1, NOW());
__runq_remove(svc);
+ }
else if ( test_bit(__CSFLAG_delayed_runq_add, &svc->flags) )
clear_bit(__CSFLAG_delayed_runq_add, &svc->flags);
}
@@ -803,6 +826,8 @@ csched_vcpu_wake(const struct scheduler

now = NOW();

+ update_load(ops, svc->rqd, 1, now);
+
/* Put the VCPU on the runq */
runq_insert(ops, vc->processor, svc);
runq_tickle(ops, vc->processor, svc, now);
@@ -841,6 +866,8 @@ csched_context_saved(const struct schedu
runq_insert(ops, vc->processor, svc);
runq_tickle(ops, vc->processor, svc, now);
}
+ else if ( !is_idle_vcpu(vc) )
+ update_load(ops, svc->rqd, -1, now);

vcpu_schedule_unlock_irq(vc);
}
@@ -1209,6 +1236,9 @@ csched_schedule(
/* Update the idle mask if necessary */
if ( !cpu_isset(cpu, rqd->idle) )
cpu_set(cpu, rqd->idle);
+ /* Make sure avgload gets updated periodically even
+ * if there's no activity */
+ update_load(ops, rqd, 0, now);
}

/*
@@ -1287,10 +1317,12 @@ csched_dump(const struct scheduler *ops)
{
printk("Runqueue %d:\n"
"\tncpus = %u\n"
- "\tmax_weight = %d\n",
+ "\tmax_weight = %d\n"
+ "\tload = %d\n",
i,
cpus_weight(prv->rqd[i].active),
- prv->rqd[i].max_weight);
+ prv->rqd[i].max_weight,
+ prv->rqd[i].load);

}
/* FIXME: Locking! */

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