On Tue, 2018-04-10 at 16:25 +0100, George Dunlap wrote: > On 04/10/2018 12:29 PM, Dario Faggioli wrote: > > > One thing we might consider doing is implementing the migrate() > callback > for the Credit scheduler, and just have it make a bunch of sanity > checks > (v->processor lock held, new_cpu lock held, vcpu not on any runqueue, > &c). > So, it turns out that I have to run. :-/
I hacked the attached patch rather quickly, but only compile tested it... And I'm pretty tired, so I can't guarantee all the BUG_ON()s are correct, nor that they are the proper ones to (potentially) catch the issue. So, Olaf, if you're fancy giving this a tray anyway, well, go ahead. If it does not work, though, get rid of it... and I'll craft a better one tomorrow. :-( Regards, Dario -- <<This happens because I choose it to happen!>> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Software Engineer @ SUSE https://www.suse.com/
commit 52bd39c760ce6664186bc9d67bcc6a8eed11f792
Author: Dario Faggioli <dfaggi...@suse.com>
Date: Tue Apr 10 18:59:28 2018 +0200
xen: credit: implement SCHED_OP(migrate)
with just sanity checking in it, to catch a race.
Signed-off-by: Dario Faggioli <dfaggi...@suse.com>
diff --git a/xen/common/sched_credit.c b/xen/common/sched_credit.c
index 9bc638c09c..5dcf530c24 100644
--- a/xen/common/sched_credit.c
+++ b/xen/common/sched_credit.c
@@ -867,6 +867,16 @@ _csched_cpu_pick(const struct scheduler *ops, struct vcpu *vc, bool_t commit)
return cpu;
}
+static void
+csched_vcpu_migrate(const struct scheduler *ops, struct vcpu *vc,
+ unsigned int new_cpu)
+{
+ BUG_ON(vc->is_running);
+ BUG_ON(test_bit(_VPF_migrating, &vc->pause_flags));
+ BUG_ON(__vcpu_on_runq(CSCHED_VCPU(vc)));
+ BUG_ON(CSCHED_VCPU(vc) == CSCHED_VCPU(curr_on_cpu(vc->processor)));
+}
+
static int
csched_cpu_pick(const struct scheduler *ops, struct vcpu *vc)
{
@@ -2278,6 +2288,7 @@ static const struct scheduler sched_credit_def = {
.adjust_global = csched_sys_cntl,
.pick_cpu = csched_cpu_pick,
+ .migrate = csched_vcpu_migrate,
.do_schedule = csched_schedule,
.dump_cpu_state = csched_dump_pcpu,
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