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    SubjectRe: [Xen-devel] [PATCH v6 10/11] x86, xen: support vcpu preempted check
    On Fri, Oct 28, 2016 at 04:11:26AM -0400, Pan Xinhui wrote:
    > From: Juergen Gross <jgross@suse.com>
    >
    > 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 <jgross@suse.com>
    > Signed-off-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
    > ---
    > 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;
    > }
    >
    > -

    Spurious change.
    > /*
    > * 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;
    > }
    >
    > /*
    > --
    > 2.4.11
    >
    >
    > _______________________________________________
    > Xen-devel mailing list
    > Xen-devel@lists.xen.org
    > https://lists.xen.org/xen-devel

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