| Message ID | 20200511112829.5500-3-jgross@suse.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | xen: Fix some bugs in scheduling | expand |
On 11.05.2020 13:28, Juergen Gross wrote: > With support of core scheduling sched_unit_migrate_finish() gained a > call of sync_vcpu_execstate() as it was believed to be called as a > result of vcpu migration in any case. > > In case of migrating a vcpu away from a physical cpu for a short period > of time only this might not be true, so drop the call and let the lazy > state syncing do its job. Replying here instead of on the patch 3 thread (and I'm sorry for mixing up function names there): By saying "for a short period of time only", do you imply without ever getting scheduled on the new (temporary) CPU? If so, I think I understand this change now, but then this could do with saying here. If not, I'm afraid I'm still lost. Jan
On 14.05.20 15:57, Jan Beulich wrote: > On 11.05.2020 13:28, Juergen Gross wrote: >> With support of core scheduling sched_unit_migrate_finish() gained a >> call of sync_vcpu_execstate() as it was believed to be called as a >> result of vcpu migration in any case. >> >> In case of migrating a vcpu away from a physical cpu for a short period >> of time only this might not be true, so drop the call and let the lazy >> state syncing do its job. > > Replying here instead of on the patch 3 thread (and I'm sorry > for mixing up function names there): By saying "for a short > period of time only", do you imply without ever getting scheduled > on the new (temporary) CPU? If so, I think I understand this > change now, but then this could do with saying here. If not, I'm > afraid I'm still lost. I'll change the commit message to: ... for a short period of time only without ever being scheduled on the selected new cpu ... Juergen
On 14.05.2020 16:21, Jürgen Groß wrote: > On 14.05.20 15:57, Jan Beulich wrote: >> On 11.05.2020 13:28, Juergen Gross wrote: >>> With support of core scheduling sched_unit_migrate_finish() gained a >>> call of sync_vcpu_execstate() as it was believed to be called as a >>> result of vcpu migration in any case. >>> >>> In case of migrating a vcpu away from a physical cpu for a short period >>> of time only this might not be true, so drop the call and let the lazy >>> state syncing do its job. >> >> Replying here instead of on the patch 3 thread (and I'm sorry >> for mixing up function names there): By saying "for a short >> period of time only", do you imply without ever getting scheduled >> on the new (temporary) CPU? If so, I think I understand this >> change now, but then this could do with saying here. If not, I'm >> afraid I'm still lost. > > I'll change the commit message to: > > ... for a short period of time only without ever being scheduled on the > selected new cpu ... And then Reviewed-by: Jan Beulich <jbeulich@suse.com> for both this one and patch 3 (ideally with the one unnecessary hunk dropped). Jan
diff --git a/xen/common/sched/core.c b/xen/common/sched/core.c index 5df66cbf9b..cb49a8bc02 100644 --- a/xen/common/sched/core.c +++ b/xen/common/sched/core.c @@ -1078,12 +1078,7 @@ static void sched_unit_migrate_finish(struct sched_unit *unit) sched_spin_unlock_double(old_lock, new_lock, flags); if ( old_cpu != new_cpu ) - { - /* Vcpus are moved to other pcpus, commit their states to memory. */ - for_each_sched_unit_vcpu ( unit, v ) - sync_vcpu_execstate(v); sched_move_irqs(unit); - } /* Wake on new CPU. */ for_each_sched_unit_vcpu ( unit, v )
With support of core scheduling sched_unit_migrate_finish() gained a call of sync_vcpu_execstate() as it was believed to be called as a result of vcpu migration in any case. In case of migrating a vcpu away from a physical cpu for a short period of time only this might not be true, so drop the call and let the lazy state syncing do its job. Signed-off-by: Juergen Gross <jgross@suse.com> --- V2: - new patch --- xen/common/sched/core.c | 5 ----- 1 file changed, 5 deletions(-)