Re: [PATCH RFC v5 5/8] pvqspinlock, x86: Enable unfair queue spinlock in a KVM guest
From: Konrad Rzeszutek Wilk <hidden>
Date: 2014-02-26 17:08:59
Also in:
linux-arch
On Wed, Feb 26, 2014 at 10:14:25AM -0500, Waiman Long wrote:
quoted hunk
This patch adds a KVM init function to activate the unfair queue spinlock in a KVM guest when the PARAVIRT_UNFAIR_LOCKS kernel config option is selected. Signed-off-by: Waiman Long <redacted> --- arch/x86/kernel/kvm.c | 17 +++++++++++++++++ 1 files changed, 17 insertions(+), 0 deletions(-)diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index 713f1b3..a489140 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c@@ -826,3 +826,20 @@ static __init int kvm_spinlock_init_jump(void) early_initcall(kvm_spinlock_init_jump); #endif /* CONFIG_PARAVIRT_SPINLOCKS */ + +#ifdef CONFIG_PARAVIRT_UNFAIR_LOCKS +/* + * Enable unfair lock if running in a real para-virtualized environment + */ +static __init int kvm_unfair_locks_init_jump(void) +{ + if (!kvm_para_available()) + return 0;
I think you also need to check for !kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)? Otherwise you might enable this, but the kicker function won't be enabled.
+ + static_key_slow_inc(¶virt_unfairlocks_enabled); + printk(KERN_INFO "KVM setup unfair spinlock\n"); + + return 0; +} +early_initcall(kvm_unfair_locks_init_jump); +#endif -- 1.7.1