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Commit 13fb5927 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

kvm: x86: disable shattered huge page recovery for PREEMPT_RT. 



If a huge page is recovered (and becomes no executable) while another
thread is executing it, the resulting contention on mmu_lock can cause
latency spikes.  Disabling recovery for PREEMPT_RT kernels fixes this
issue.

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 8c5bd25b

arch/x86/kvm/mmu.c

+5 −0
Original line number Diff line number Diff line
@@ -51,7 +51,12 @@ 
extern bool itlb_multihit_kvm_mitigation;



static int __read_mostly nx_huge_pages = -1;

#ifdef CONFIG_PREEMPT_RT

/* Recovery can cause latency spikes, disable it for PREEMPT_RT.  */

static uint __read_mostly nx_huge_pages_recovery_ratio = 0;

#else

static uint __read_mostly nx_huge_pages_recovery_ratio = 60;

#endif



static int set_nx_huge_pages(const char *val, const struct kernel_param *kp);

static int set_nx_huge_pages_recovery_ratio(const char *val, const struct kernel_param *kp);