From de7689cf8f3820b34088da3b22ce1a548dda2fc5 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Wed, 2 Nov 2016 05:08:37 -0400 Subject: x86/xen: Support the vCPU preemption check Support the vcpu_is_preempted() functionality under Xen. This will enhance lock performance on overcommitted hosts (more runnable vCPUs than physical CPUs in the system) as doing busy waits for preempted vCPUs will hurt system performance far worse than early yielding. A quick test (4 vCPUs on 1 physical CPU doing a parallel build job with "make -j 8") reduced system time by about 5% with this patch. Signed-off-by: Juergen Gross Signed-off-by: Pan Xinhui Signed-off-by: Peter Zijlstra (Intel) Cc: David.Laight@ACULAB.COM Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: benh@kernel.crashing.org Cc: boqun.feng@gmail.com Cc: borntraeger@de.ibm.com Cc: bsingharora@gmail.com Cc: dave@stgolabs.net Cc: kernellwp@gmail.com Cc: konrad.wilk@oracle.com Cc: linuxppc-dev@lists.ozlabs.org Cc: mpe@ellerman.id.au Cc: paulmck@linux.vnet.ibm.com Cc: paulus@samba.org Cc: pbonzini@redhat.com Cc: rkrcmar@redhat.com Cc: virtualization@lists.linux-foundation.org Cc: will.deacon@arm.com Cc: xen-devel-request@lists.xenproject.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1478077718-37424-11-git-send-email-xinhui.pan@linux.vnet.ibm.com Signed-off-by: Ingo Molnar --- arch/x86/xen/spinlock.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c index 3d6e006..74756bb 100644 --- a/arch/x86/xen/spinlock.c +++ b/arch/x86/xen/spinlock.c @@ -114,7 +114,6 @@ void xen_uninit_lock_cpu(int cpu) per_cpu(irq_name, cpu) = NULL; } - /* * Our init of PV spinlocks is split in two init functions due to us * using paravirt patching and jump labels patching and having to do @@ -137,6 +136,8 @@ void __init xen_init_spinlocks(void) pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock); pv_lock_ops.wait = xen_qlock_wait; pv_lock_ops.kick = xen_qlock_kick; + + pv_lock_ops.vcpu_is_preempted = xen_vcpu_stolen; } /* -- cgit v1.1