diff options
authorDavid Vrabel <>2012-04-26 19:44:06 +0100
committerKonrad Rzeszutek Wilk <>2012-04-27 16:04:21 -0400
commit7eb7ce4d2e8991aff4ecb71a81949a907ca755ac (patch)
parentb930fe5e1f5646e071facda70b25b137ebeae5af (diff)
xen: correctly check for pending events when restoring irq flags
In xen_restore_fl_direct(), xen_force_evtchn_callback() was being called even if no events were pending. This resulted in (depending on workload) about a 100 times as many xen_version hypercalls as necessary. Fix this by correcting the sense of the conditional jump. This seems to give a significant performance benefit for some workloads. There is some subtle tricksy "..since the check here is trying to check both pending and masked in a single cmpw, but I think this is correct. It will call check_events now only when the combined mask+pending word is 0x0001 (aka unmasked, pending)." (Ian) CC: Acked-by: Ian Campbell <> Signed-off-by: David Vrabel <> Signed-off-by: Konrad Rzeszutek Wilk <>
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/xen/xen-asm.S b/arch/x86/xen/xen-asm.S
index 79d7362ad6d1..3e45aa000718 100644
--- a/arch/x86/xen/xen-asm.S
+++ b/arch/x86/xen/xen-asm.S
@@ -96,7 +96,7 @@ ENTRY(xen_restore_fl_direct)
/* check for unmasked and pending */
cmpw $0x0001, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_pending
- jz 1f
+ jnz 1f
2: call check_events