On 08/01/2015 18:41, Marcelo Tosatti wrote:
Paolo?
And cover letter is a bit misleading: The condition does nothing to
guarantee TSC based __delay() loop. (Right now, __delay() = delay_tsc()
whenever the hardware has TSC, regardless of stability, thus always.)
OK.
Yes, because of
On Mon, Jan 05, 2015 at 07:12:36PM +0100, Radim Krcmar wrote:
2014-12-23 15:58-0500, Marcelo Tosatti:
For the hrtimer which emulates the tscdeadline timer in the guest,
add an option to advance expiration, and busy spin on VM-entry waiting
for the actual expiration time to elapse.
This
2014-12-23 15:58-0500, Marcelo Tosatti:
For the hrtimer which emulates the tscdeadline timer in the guest,
add an option to advance expiration, and busy spin on VM-entry waiting
for the actual expiration time to elapse.
This allows achieving low latencies in cyclictest (or any scenario
2015-01-05 19:12+0100, Radim Krcmar:
(Right now, __delay() = delay_tsc()
whenever the hardware has TSC, regardless of stability, thus always.)
(For quantifiers' sake, there also is 'tsc_disabled' variable.)
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On 18/12/2014 13:24, Marcelo Tosatti wrote:
True. I can change to a direct wait if that is preferred.
What about this:
guest_tsc = kvm_x86_ops-read_l1_tsc(vcpu, native_read_tsc());
trace_kvm_wait_lapic_expire(vcpu-vcpu_id, guest_tsc - tsc_deadline);
/* We know that
For the hrtimer which emulates the tscdeadline timer in the guest,
add an option to advance expiration, and busy spin on VM-entry waiting
for the actual expiration time to elapse.
This allows achieving low latencies in cyclictest (or any scenario
which requires strict timing regarding timer
On Wed, Dec 17, 2014 at 08:36:27PM +0100, Radim Krcmar wrote:
2014-12-17 15:41-0200, Marcelo Tosatti:
On Wed, Dec 17, 2014 at 03:58:13PM +0100, Radim Krcmar wrote:
2014-12-16 09:08-0500, Marcelo Tosatti:
+ tsc_deadline = apic-lapic_timer.expired_tscdeadline;
+
2014-12-16 09:08-0500, Marcelo Tosatti:
For the hrtimer which emulates the tscdeadline timer in the guest,
add an option to advance expiration, and busy spin on VM-entry waiting
for the actual expiration time to elapse.
This allows achieving low latencies in cyclictest (or any scenario
On Wed, Dec 17, 2014 at 03:58:13PM +0100, Radim Krcmar wrote:
2014-12-16 09:08-0500, Marcelo Tosatti:
For the hrtimer which emulates the tscdeadline timer in the guest,
add an option to advance expiration, and busy spin on VM-entry waiting
for the actual expiration time to elapse.
This
On 17/12/2014 18:41, Marcelo Tosatti wrote:
Btw. simple automatic delta tuning had worse results?
Haven't tried automatic tuning.
So what happens on a realtime environment is this: you execute the fixed
number of instructions from interrupt handling all the way to VM-entry.
Well,
2014-12-17 15:41-0200, Marcelo Tosatti:
On Wed, Dec 17, 2014 at 03:58:13PM +0100, Radim Krcmar wrote:
2014-12-16 09:08-0500, Marcelo Tosatti:
+ tsc_deadline = apic-lapic_timer.expired_tscdeadline;
+ apic-lapic_timer.expired_tscdeadline = 0;
+ guest_tsc = kvm_x86_ops-read_l1_tsc(vcpu,
For the hrtimer which emulates the tscdeadline timer in the guest,
add an option to advance expiration, and busy spin on VM-entry waiting
for the actual expiration time to elapse.
This allows achieving low latencies in cyclictest (or any scenario
which requires strict timing regarding timer
On 15/12/2014 23:06, Marcelo Tosatti wrote:
For the hrtimer which emulates the tscdeadline timer in the guest,
add an option to advance expiration, and busy spin on VM-entry waiting
for the actual expiration time to elapse.
This allows achieving low latencies in cyclictest (or any scenario
On Tue, Dec 16, 2014 at 03:34:22PM +0100, Paolo Bonzini wrote:
On 15/12/2014 23:06, Marcelo Tosatti wrote:
For the hrtimer which emulates the tscdeadline timer in the guest,
add an option to advance expiration, and busy spin on VM-entry waiting
for the actual expiration time to elapse.
On 16/12/2014 16:13, Marcelo Tosatti wrote:
So perhaps you can get rid of patch 1 and check
kvm_apic_vid_enabled(vcpu-kvm):
if (k_a_v_e(vcpu-kvm)
return true;
if (apic_test_vector(vec, apic-regs + APIC_ISR))
return true;
Does this sound correct?
*
For the hrtimer which emulates the tscdeadline timer in the guest,
add an option to advance expiration, and busy spin on VM-entry waiting
for the actual expiration time to elapse.
This allows achieving low latencies in cyclictest (or any scenario
which requires strict timing regarding timer
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