| Message ID | 146918909364.19443.6394900696027710502.stgit@Solace.fritz.box (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 22/07/16 13:04, Dario Faggioli wrote: > The ASSERT() made effective by b5b5876619bd8ec2e > ("xen: credit2: fix two s_time_t handling issues > in load balancing") triggers for b_avgload (spotted > by OSSTest). > > b_avgload is where we store the prediction of how > the load of a runqueue will look like in the medium > to long term, because of a vcpu being added to or > removed from there. > > On vcpu removal, saturate down b_avgload to zero, > as it makes very few sense to predict that the > load of a runqueue will at some point become negative! > > Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com> Acked-by: George Dunlap <george.dunlap@citrix.com> Wei, do you want to apply it? Thanks, -George > --- > Cc: George Dunlap <george.dunlap@eu.citrix.com> > Cc: Wei Liu <wei.liu2@citrix.com> > --- > xen/common/sched_credit2.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/xen/common/sched_credit2.c b/xen/common/sched_credit2.c > index b92226c..1d79de0 100644 > --- a/xen/common/sched_credit2.c > +++ b/xen/common/sched_credit2.c > @@ -1323,14 +1323,16 @@ runq_assign(const struct scheduler *ops, struct vcpu *vc) > static void > __runq_deassign(struct csched2_vcpu *svc) > { > + struct csched2_runqueue_data *rqd = svc->rqd; > + > ASSERT(!__vcpu_on_runq(svc)); > ASSERT(!(svc->flags & CSFLAG_scheduled)); > > list_del_init(&svc->rqd_elem); > - update_max_weight(svc->rqd, 0, svc->weight); > + update_max_weight(rqd, 0, svc->weight); > > /* Expected new load based on removing this vcpu */ > - svc->rqd->b_avgload -= svc->avgload; > + rqd->b_avgload = max_t(s_time_t, rqd->b_avgload - svc->avgload, 0); > > svc->rqd = NULL; > } > @@ -1590,7 +1592,7 @@ csched2_cpu_pick(const struct scheduler *ops, struct vcpu *vc) > if ( rqd == svc->rqd ) > { > if ( cpumask_intersects(vc->cpu_hard_affinity, &rqd->active) ) > - rqd_avgload = rqd->b_avgload - svc->avgload; > + rqd_avgload = max_t(s_time_t, rqd->b_avgload - svc->avgload, 0); > } > else if ( spin_trylock(&rqd->lock) ) > { >
On Fri, Jul 22, 2016 at 01:34:27PM +0100, George Dunlap wrote: > On 22/07/16 13:04, Dario Faggioli wrote: > > The ASSERT() made effective by b5b5876619bd8ec2e > > ("xen: credit2: fix two s_time_t handling issues > > in load balancing") triggers for b_avgload (spotted > > by OSSTest). > > > > b_avgload is where we store the prediction of how > > the load of a runqueue will look like in the medium > > to long term, because of a vcpu being added to or > > removed from there. > > > > On vcpu removal, saturate down b_avgload to zero, > > as it makes very few sense to predict that the > > load of a runqueue will at some point become negative! > > > > Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com> > > Acked-by: George Dunlap <george.dunlap@citrix.com> > > Wei, do you want to apply it? > I will apply it with your ack.
diff --git a/xen/common/sched_credit2.c b/xen/common/sched_credit2.c index b92226c..1d79de0 100644 --- a/xen/common/sched_credit2.c +++ b/xen/common/sched_credit2.c @@ -1323,14 +1323,16 @@ runq_assign(const struct scheduler *ops, struct vcpu *vc) static void __runq_deassign(struct csched2_vcpu *svc) { + struct csched2_runqueue_data *rqd = svc->rqd; + ASSERT(!__vcpu_on_runq(svc)); ASSERT(!(svc->flags & CSFLAG_scheduled)); list_del_init(&svc->rqd_elem); - update_max_weight(svc->rqd, 0, svc->weight); + update_max_weight(rqd, 0, svc->weight); /* Expected new load based on removing this vcpu */ - svc->rqd->b_avgload -= svc->avgload; + rqd->b_avgload = max_t(s_time_t, rqd->b_avgload - svc->avgload, 0); svc->rqd = NULL; } @@ -1590,7 +1592,7 @@ csched2_cpu_pick(const struct scheduler *ops, struct vcpu *vc) if ( rqd == svc->rqd ) { if ( cpumask_intersects(vc->cpu_hard_affinity, &rqd->active) ) - rqd_avgload = rqd->b_avgload - svc->avgload; + rqd_avgload = max_t(s_time_t, rqd->b_avgload - svc->avgload, 0); } else if ( spin_trylock(&rqd->lock) ) {
The ASSERT() made effective by b5b5876619bd8ec2e ("xen: credit2: fix two s_time_t handling issues in load balancing") triggers for b_avgload (spotted by OSSTest). b_avgload is where we store the prediction of how the load of a runqueue will look like in the medium to long term, because of a vcpu being added to or removed from there. On vcpu removal, saturate down b_avgload to zero, as it makes very few sense to predict that the load of a runqueue will at some point become negative! Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com> --- Cc: George Dunlap <george.dunlap@eu.citrix.com> Cc: Wei Liu <wei.liu2@citrix.com> --- xen/common/sched_credit2.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)