[PATCH v3] KVM: X86: Lower the default timer frequency limit to 200us

[Wanpeng Li]

From: Wanpeng Li <wanpengli@xxxxxxxxxxx>

Anthoine reported:
 The period used by Windows change over time but it can be 1 
 milliseconds or less. I saw the limit_periodic_timer_frequency 
 print so 500 microseconds is sometimes reached.

As suggested by Paolo, lower the default timer frequency limit to a
smaller interval of 200 us (5000 Hz) to leave some headroom. This
is required due to Windows 10 changing the scheduler tick limit
from 1024 Hz to 2048 Hz.

Reported-by: Anthoine Bourgeois <anthoine.bourgeois@xxxxxxxxxxxxxxx>
Suggested-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> 
Reviewed-by: Darren Kenny <darren.kenny@xxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>
Cc: Anthoine Bourgeois <anthoine.bourgeois@xxxxxxxxxxxxxxx>
Cc: Darren Kenny <darren.kenny@xxxxxxxxxx>
Cc: Jan Kiszka <jan.kiszka@xxxxxx>
Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
---
v2 -> v3:
 * update patch subject and description
v1 -> v2:
 * update patch subject and description

 arch/x86/kvm/x86.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 51ecd38..dc47073 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -114,7 +114,7 @@ module_param(ignore_msrs, bool, S_IRUGO | S_IWUSR);
 static bool __read_mostly report_ignored_msrs = true;
 module_param(report_ignored_msrs, bool, S_IRUGO | S_IWUSR);
 
-unsigned int min_timer_period_us = 500;
+unsigned int min_timer_period_us = 200;
 module_param(min_timer_period_us, uint, S_IRUGO | S_IWUSR);
 
 static bool __read_mostly kvmclock_periodic_sync = true;
-- 
2.7.4