Re: [PATCH v5 0/4] KVM: LAPIC: Implement Exitless Timer
On Wed, 3 Jul 2019 at 08:47, Wanpeng Li wrote:
>
> On Wed, 3 Jul 2019 at 06:23, Marcelo Tosatti wrote:
> >
> > On Tue, Jul 02, 2019 at 06:38:56PM +0200, Paolo Bonzini wrote:
> > > On 21/06/19 11:39, Wanpeng Li wrote:
> > > > Dedicated instances are currently disturbed by unnecessary jitter due
> > > > to the emulated lapic timers fire on the same pCPUs which vCPUs
> > > > resident.
> > > > There is no hardware virtual timer on Intel for guest like ARM. Both
> > > > programming timer in guest and the emulated timer fires incur vmexits.
> > > > This patchset tries to avoid vmexit which is incurred by the emulated
> > > > timer fires in dedicated instance scenario.
> > > >
> > > > When nohz_full is enabled in dedicated instances scenario, the unpinned
> > > > timer will be moved to the nearest busy housekeepers after commit
> > > > 9642d18eee2cd (nohz: Affine unpinned timers to housekeepers) and commit
> > > > 444969223c8 ("sched/nohz: Fix affine unpinned timers mess"). However,
> > > > KVM always makes lapic timer pinned to the pCPU which vCPU residents,
> > > > the
> > > > reason is explained by commit 61abdbe0 (kvm: x86: make lapic hrtimer
> > > > pinned). Actually, these emulated timers can be offload to the
> > > > housekeeping
> > > > cpus since APICv is really common in recent years. The guest timer
> > > > interrupt
> > > > is injected by posted-interrupt which is delivered by housekeeping cpu
> > > > once the emulated timer fires.
> > > >
> > > > The host admin should fine tuned, e.g. dedicated instances scenario w/
> > > > nohz_full cover the pCPUs which vCPUs resident, several pCPUs surplus
> > > > for busy housekeeping, disable mwait/hlt/pause vmexits to keep in
> > > > non-root
> > > > mode, ~3% redis performance benefit can be observed on Skylake server.
> > >
> > > Marcelo,
> > >
> > > does this patch work for you or can you still see the oops?
> >
> > Hi Paolo,
> >
> > No more oopses with kvm/queue. Can you include:
>
> Cool, thanks for the confirm, Marcelo!
>
> >
> > Index: kvm/arch/x86/kvm/lapic.c
> > ===
> > --- kvm.orig/arch/x86/kvm/lapic.c
> > +++ kvm/arch/x86/kvm/lapic.c
> > @@ -124,8 +124,7 @@ static inline u32 kvm_x2apic_id(struct k
> >
> > bool posted_interrupt_inject_timer(struct kvm_vcpu *vcpu)
> > {
> > - return pi_inject_timer && kvm_vcpu_apicv_active(vcpu) &&
> > - kvm_hlt_in_guest(vcpu->kvm);
> > + return pi_inject_timer && kvm_vcpu_apicv_active(vcpu);
> > }
> > EXPORT_SYMBOL_GPL(posted_interrupt_inject_timer);
> >
> > However, for some reason (hrtimer subsystems responsability) with
> > cyclictest -i 200
> > on the guest, the timer runs on the local CPU:
> >
> >CPU 1/KVM-9454 [003] d..2 881.674196: get_nohz_timer_target:
> > get_nohz_timer_target 3->0
> >CPU 1/KVM-9454 [003] d..2 881.674200: get_nohz_timer_target:
> > get_nohz_timer_target 3->0
> >CPU 1/KVM-9454 [003] d.h. 881.674387: apic_timer_fn
> > <-__hrtimer_run_queues
> >CPU 1/KVM-9454 [003] d..2 881.674393: get_nohz_timer_target:
> > get_nohz_timer_target 3->0
> >CPU 1/KVM-9454 [003] d..2 881.674395: get_nohz_timer_target:
> > get_nohz_timer_target 3->0
> >CPU 1/KVM-9454 [003] d..2 881.674399: get_nohz_timer_target:
> > get_nohz_timer_target 3->0
> >CPU 1/KVM-9454 [003] d.h. 881.674586: apic_timer_fn
> > <-__hrtimer_run_queues
> >CPU 1/KVM-9454 [003] d..2 881.674593: get_nohz_timer_target:
> > get_nohz_timer_target 3->0
> >CPU 1/KVM-9454 [003] d..2 881.674595: get_nohz_timer_target:
> > get_nohz_timer_target 3->0
> >CPU 1/KVM-9454 [003] d..2 881.674599: get_nohz_timer_target:
> > get_nohz_timer_target 3->0
> >CPU 1/KVM-9454 [003] d.h. 881.674787: apic_timer_fn
> > <-__hrtimer_run_queues
> >CPU 1/KVM-9454 [003] d..2 881.674793: get_nohz_timer_target:
> > get_nohz_timer_target 3->0
> >CPU 1/KVM-9454 [003] d..2 881.674795: get_nohz_timer_target:
> > get_nohz_timer_target 3->0
> >
> > But on boot:
> >
> >CPU 1/KVM-9454 [003] d..2 578.625394: get_nohz_timer_target:
> > get_nohz_timer_target 3->0
> > -0 [000] d.h1 578.626390: apic_timer_fn
> > <-__hrtimer_run_queues
> > -0 [000] d.h1 578.626394:
> > apic_timer_fn<-__hrtimer_run_queues
> >CPU 1/KVM-9454 [003] d..2 578.626401: get_nohz_timer_target:
> > get_nohz_timer_target 3->0
> > -0 [000] d.h1 578.628397: apic_timer_fn
> > <-__hrtimer_run_queues
> >CPU 1/KVM-9454 [003] d..2 578.628407: get_nohz_timer_target:
> > get_nohz_timer_target 3->0
> > -0 [000] d.h1 578.631403: apic_timer_fn
> > <-__hrtimer_run_queues
> >CPU 1/KVM-9454 [003] d..2 578.631413: get_nohz_timer_target:
> > get_nohz_timer_target 3->0
> > -0 [000] d.h1 578.635409: apic_timer_fn
> > <-__hrtimer_run_queues
> >CPU 1/KV
Re: [PATCH v5 0/4] KVM: LAPIC: Implement Exitless Timer
On Tue, Jul 02, 2019 at 06:38:56PM +0200, Paolo Bonzini wrote:
> On 21/06/19 11:39, Wanpeng Li wrote:
> > Dedicated instances are currently disturbed by unnecessary jitter due
> > to the emulated lapic timers fire on the same pCPUs which vCPUs resident.
> > There is no hardware virtual timer on Intel for guest like ARM. Both
> > programming timer in guest and the emulated timer fires incur vmexits.
> > This patchset tries to avoid vmexit which is incurred by the emulated
> > timer fires in dedicated instance scenario.
> >
> > When nohz_full is enabled in dedicated instances scenario, the unpinned
> > timer will be moved to the nearest busy housekeepers after commit
> > 9642d18eee2cd (nohz: Affine unpinned timers to housekeepers) and commit
> > 444969223c8 ("sched/nohz: Fix affine unpinned timers mess"). However,
> > KVM always makes lapic timer pinned to the pCPU which vCPU residents, the
> > reason is explained by commit 61abdbe0 (kvm: x86: make lapic hrtimer
> > pinned). Actually, these emulated timers can be offload to the housekeeping
> > cpus since APICv is really common in recent years. The guest timer
> > interrupt
> > is injected by posted-interrupt which is delivered by housekeeping cpu
> > once the emulated timer fires.
> >
> > The host admin should fine tuned, e.g. dedicated instances scenario w/
> > nohz_full cover the pCPUs which vCPUs resident, several pCPUs surplus
> > for busy housekeeping, disable mwait/hlt/pause vmexits to keep in non-root
> > mode, ~3% redis performance benefit can be observed on Skylake server.
>
> Marcelo,
>
> does this patch work for you or can you still see the oops?
Hi Paolo,
No more oopses with kvm/queue. Can you include:
Index: kvm/arch/x86/kvm/lapic.c
===
--- kvm.orig/arch/x86/kvm/lapic.c
+++ kvm/arch/x86/kvm/lapic.c
@@ -124,8 +124,7 @@ static inline u32 kvm_x2apic_id(struct k
bool posted_interrupt_inject_timer(struct kvm_vcpu *vcpu)
{
- return pi_inject_timer && kvm_vcpu_apicv_active(vcpu) &&
- kvm_hlt_in_guest(vcpu->kvm);
+ return pi_inject_timer && kvm_vcpu_apicv_active(vcpu);
}
EXPORT_SYMBOL_GPL(posted_interrupt_inject_timer);
However, for some reason (hrtimer subsystems responsability) with cyclictest -i
200
on the guest, the timer runs on the local CPU:
CPU 1/KVM-9454 [003] d..2 881.674196: get_nohz_timer_target:
get_nohz_timer_target 3->0
CPU 1/KVM-9454 [003] d..2 881.674200: get_nohz_timer_target:
get_nohz_timer_target 3->0
CPU 1/KVM-9454 [003] d.h. 881.674387: apic_timer_fn
<-__hrtimer_run_queues
CPU 1/KVM-9454 [003] d..2 881.674393: get_nohz_timer_target:
get_nohz_timer_target 3->0
CPU 1/KVM-9454 [003] d..2 881.674395: get_nohz_timer_target:
get_nohz_timer_target 3->0
CPU 1/KVM-9454 [003] d..2 881.674399: get_nohz_timer_target:
get_nohz_timer_target 3->0
CPU 1/KVM-9454 [003] d.h. 881.674586: apic_timer_fn
<-__hrtimer_run_queues
CPU 1/KVM-9454 [003] d..2 881.674593: get_nohz_timer_target:
get_nohz_timer_target 3->0
CPU 1/KVM-9454 [003] d..2 881.674595: get_nohz_timer_target:
get_nohz_timer_target 3->0
CPU 1/KVM-9454 [003] d..2 881.674599: get_nohz_timer_target:
get_nohz_timer_target 3->0
CPU 1/KVM-9454 [003] d.h. 881.674787: apic_timer_fn
<-__hrtimer_run_queues
CPU 1/KVM-9454 [003] d..2 881.674793: get_nohz_timer_target:
get_nohz_timer_target 3->0
CPU 1/KVM-9454 [003] d..2 881.674795: get_nohz_timer_target:
get_nohz_timer_target 3->0
But on boot:
CPU 1/KVM-9454 [003] d..2 578.625394: get_nohz_timer_target:
get_nohz_timer_target 3->0
-0 [000] d.h1 578.626390: apic_timer_fn
<-__hrtimer_run_queues
-0 [000] d.h1 578.626394:
apic_timer_fn<-__hrtimer_run_queues
CPU 1/KVM-9454 [003] d..2 578.626401: get_nohz_timer_target:
get_nohz_timer_target 3->0
-0 [000] d.h1 578.628397: apic_timer_fn
<-__hrtimer_run_queues
CPU 1/KVM-9454 [003] d..2 578.628407: get_nohz_timer_target:
get_nohz_timer_target 3->0
-0 [000] d.h1 578.631403: apic_timer_fn
<-__hrtimer_run_queues
CPU 1/KVM-9454 [003] d..2 578.631413: get_nohz_timer_target:
get_nohz_timer_target 3->0
-0 [000] d.h1 578.635409: apic_timer_fn
<-__hrtimer_run_queues
CPU 1/KVM-9454 [003] d..2 578.635419: get_nohz_timer_target:
get_nohz_timer_target 3->0
-0 [000] d.h1 578.640415: apic_timer_fn
<-__hrtimer_run_queues
Thanks.
Re: [PATCH v5 0/4] KVM: LAPIC: Implement Exitless Timer
On Wed, 3 Jul 2019 at 06:23, Marcelo Tosatti wrote:
>
> On Tue, Jul 02, 2019 at 06:38:56PM +0200, Paolo Bonzini wrote:
> > On 21/06/19 11:39, Wanpeng Li wrote:
> > > Dedicated instances are currently disturbed by unnecessary jitter due
> > > to the emulated lapic timers fire on the same pCPUs which vCPUs resident.
> > > There is no hardware virtual timer on Intel for guest like ARM. Both
> > > programming timer in guest and the emulated timer fires incur vmexits.
> > > This patchset tries to avoid vmexit which is incurred by the emulated
> > > timer fires in dedicated instance scenario.
> > >
> > > When nohz_full is enabled in dedicated instances scenario, the unpinned
> > > timer will be moved to the nearest busy housekeepers after commit
> > > 9642d18eee2cd (nohz: Affine unpinned timers to housekeepers) and commit
> > > 444969223c8 ("sched/nohz: Fix affine unpinned timers mess"). However,
> > > KVM always makes lapic timer pinned to the pCPU which vCPU residents, the
> > > reason is explained by commit 61abdbe0 (kvm: x86: make lapic hrtimer
> > > pinned). Actually, these emulated timers can be offload to the
> > > housekeeping
> > > cpus since APICv is really common in recent years. The guest timer
> > > interrupt
> > > is injected by posted-interrupt which is delivered by housekeeping cpu
> > > once the emulated timer fires.
> > >
> > > The host admin should fine tuned, e.g. dedicated instances scenario w/
> > > nohz_full cover the pCPUs which vCPUs resident, several pCPUs surplus
> > > for busy housekeeping, disable mwait/hlt/pause vmexits to keep in non-root
> > > mode, ~3% redis performance benefit can be observed on Skylake server.
> >
> > Marcelo,
> >
> > does this patch work for you or can you still see the oops?
>
> Hi Paolo,
>
> No more oopses with kvm/queue. Can you include:
Cool, thanks for the confirm, Marcelo!
>
> Index: kvm/arch/x86/kvm/lapic.c
> ===
> --- kvm.orig/arch/x86/kvm/lapic.c
> +++ kvm/arch/x86/kvm/lapic.c
> @@ -124,8 +124,7 @@ static inline u32 kvm_x2apic_id(struct k
>
> bool posted_interrupt_inject_timer(struct kvm_vcpu *vcpu)
> {
> - return pi_inject_timer && kvm_vcpu_apicv_active(vcpu) &&
> - kvm_hlt_in_guest(vcpu->kvm);
> + return pi_inject_timer && kvm_vcpu_apicv_active(vcpu);
> }
> EXPORT_SYMBOL_GPL(posted_interrupt_inject_timer);
>
> However, for some reason (hrtimer subsystems responsability) with cyclictest
> -i 200
> on the guest, the timer runs on the local CPU:
>
>CPU 1/KVM-9454 [003] d..2 881.674196: get_nohz_timer_target:
> get_nohz_timer_target 3->0
>CPU 1/KVM-9454 [003] d..2 881.674200: get_nohz_timer_target:
> get_nohz_timer_target 3->0
>CPU 1/KVM-9454 [003] d.h. 881.674387: apic_timer_fn
> <-__hrtimer_run_queues
>CPU 1/KVM-9454 [003] d..2 881.674393: get_nohz_timer_target:
> get_nohz_timer_target 3->0
>CPU 1/KVM-9454 [003] d..2 881.674395: get_nohz_timer_target:
> get_nohz_timer_target 3->0
>CPU 1/KVM-9454 [003] d..2 881.674399: get_nohz_timer_target:
> get_nohz_timer_target 3->0
>CPU 1/KVM-9454 [003] d.h. 881.674586: apic_timer_fn
> <-__hrtimer_run_queues
>CPU 1/KVM-9454 [003] d..2 881.674593: get_nohz_timer_target:
> get_nohz_timer_target 3->0
>CPU 1/KVM-9454 [003] d..2 881.674595: get_nohz_timer_target:
> get_nohz_timer_target 3->0
>CPU 1/KVM-9454 [003] d..2 881.674599: get_nohz_timer_target:
> get_nohz_timer_target 3->0
>CPU 1/KVM-9454 [003] d.h. 881.674787: apic_timer_fn
> <-__hrtimer_run_queues
>CPU 1/KVM-9454 [003] d..2 881.674793: get_nohz_timer_target:
> get_nohz_timer_target 3->0
>CPU 1/KVM-9454 [003] d..2 881.674795: get_nohz_timer_target:
> get_nohz_timer_target 3->0
>
> But on boot:
>
>CPU 1/KVM-9454 [003] d..2 578.625394: get_nohz_timer_target:
> get_nohz_timer_target 3->0
> -0 [000] d.h1 578.626390: apic_timer_fn
> <-__hrtimer_run_queues
> -0 [000] d.h1 578.626394:
> apic_timer_fn<-__hrtimer_run_queues
>CPU 1/KVM-9454 [003] d..2 578.626401: get_nohz_timer_target:
> get_nohz_timer_target 3->0
> -0 [000] d.h1 578.628397: apic_timer_fn
> <-__hrtimer_run_queues
>CPU 1/KVM-9454 [003] d..2 578.628407: get_nohz_timer_target:
> get_nohz_timer_target 3->0
> -0 [000] d.h1 578.631403: apic_timer_fn
> <-__hrtimer_run_queues
>CPU 1/KVM-9454 [003] d..2 578.631413: get_nohz_timer_target:
> get_nohz_timer_target 3->0
> -0 [000] d.h1 578.635409: apic_timer_fn
> <-__hrtimer_run_queues
>CPU 1/KVM-9454 [003] d..2 578.635419: get_nohz_timer_target:
> get_nohz_timer_target 3->0
> -0 [000] d.h1 578.640415: apic_timer_fn
> <-__hrtimer_run_queues
You have an idle housekeeping cpu(cpu 0), however, most of
housekeeping cpus will be busy in product environment to
Re: [PATCH v5 0/4] KVM: LAPIC: Implement Exitless Timer
On 21/06/19 11:39, Wanpeng Li wrote:
> Dedicated instances are currently disturbed by unnecessary jitter due
> to the emulated lapic timers fire on the same pCPUs which vCPUs resident.
> There is no hardware virtual timer on Intel for guest like ARM. Both
> programming timer in guest and the emulated timer fires incur vmexits.
> This patchset tries to avoid vmexit which is incurred by the emulated
> timer fires in dedicated instance scenario.
>
> When nohz_full is enabled in dedicated instances scenario, the unpinned
> timer will be moved to the nearest busy housekeepers after commit
> 9642d18eee2cd (nohz: Affine unpinned timers to housekeepers) and commit
> 444969223c8 ("sched/nohz: Fix affine unpinned timers mess"). However,
> KVM always makes lapic timer pinned to the pCPU which vCPU residents, the
> reason is explained by commit 61abdbe0 (kvm: x86: make lapic hrtimer
> pinned). Actually, these emulated timers can be offload to the housekeeping
> cpus since APICv is really common in recent years. The guest timer interrupt
> is injected by posted-interrupt which is delivered by housekeeping cpu
> once the emulated timer fires.
>
> The host admin should fine tuned, e.g. dedicated instances scenario w/
> nohz_full cover the pCPUs which vCPUs resident, several pCPUs surplus
> for busy housekeeping, disable mwait/hlt/pause vmexits to keep in non-root
> mode, ~3% redis performance benefit can be observed on Skylake server.
Marcelo,
does this patch work for you or can you still see the oops?
Thanks,
Paolo
> w/o patchset:
>
> VM-EXIT Samples Samples% Time% Min Time Max Time Avg time
>
> EXTERNAL_INTERRUPT4291649.43% 39.30% 0.47us 106.09us 0.71us (
> +- 1.09% )
>
> w/ patchset:
>
> VM-EXIT Samples Samples% Time% Min Time Max Time
> Avg time
>
> EXTERNAL_INTERRUPT6871 9.29% 2.96% 0.44us57.88us 0.72us (
> +- 4.02% )
>
> Cc: Paolo Bonzini
> Cc: Radim Krčmář
> Cc: Marcelo Tosatti
>
> v4 -> v5:
> * update patch description in patch 1/4
> * feed latest apic->lapic_timer.expired_tscdeadline to
> kvm_wait_lapic_expire()
> * squash advance timer handling to patch 2/4
>
> v3 -> v4:
> * drop the HRTIMER_MODE_ABS_PINNED, add kick after set pending timer
> * don't posted inject already-expired timer
>
> v2 -> v3:
> * disarming the vmx preemption timer when
> posted_interrupt_inject_timer_enabled()
> * check kvm_hlt_in_guest instead
>
> v1 -> v2:
> * check vcpu_halt_in_guest
> * move module parameter from kvm-intel to kvm
> * add housekeeping_enabled
> * rename apic_timer_expired_pi to kvm_apic_inject_pending_timer_irqs
>
>
> Wanpeng Li (4):
> KVM: LAPIC: Make lapic timer unpinned
> KVM: LAPIC: Inject timer interrupt via posted interrupt
> KVM: LAPIC: Ignore timer migration when lapic timer is injected by pi
> KVM: LAPIC: Don't inject already-expired timer via posted interrupt
>
> arch/x86/kvm/lapic.c| 68
> +++--
> arch/x86/kvm/lapic.h| 3 +-
> arch/x86/kvm/svm.c | 2 +-
> arch/x86/kvm/vmx/vmx.c | 5 +--
> arch/x86/kvm/x86.c | 11 ---
> arch/x86/kvm/x86.h | 2 ++
> include/linux/sched/isolation.h | 2 ++
> kernel/sched/isolation.c| 6
> 8 files changed, 67 insertions(+), 32 deletions(-)
>
[PATCH v5 0/4] KVM: LAPIC: Implement Exitless Timer
Dedicated instances are currently disturbed by unnecessary jitter due
to the emulated lapic timers fire on the same pCPUs which vCPUs resident.
There is no hardware virtual timer on Intel for guest like ARM. Both
programming timer in guest and the emulated timer fires incur vmexits.
This patchset tries to avoid vmexit which is incurred by the emulated
timer fires in dedicated instance scenario.
When nohz_full is enabled in dedicated instances scenario, the unpinned
timer will be moved to the nearest busy housekeepers after commit
9642d18eee2cd (nohz: Affine unpinned timers to housekeepers) and commit
444969223c8 ("sched/nohz: Fix affine unpinned timers mess"). However,
KVM always makes lapic timer pinned to the pCPU which vCPU residents, the
reason is explained by commit 61abdbe0 (kvm: x86: make lapic hrtimer
pinned). Actually, these emulated timers can be offload to the housekeeping
cpus since APICv is really common in recent years. The guest timer interrupt
is injected by posted-interrupt which is delivered by housekeeping cpu
once the emulated timer fires.
The host admin should fine tuned, e.g. dedicated instances scenario w/
nohz_full cover the pCPUs which vCPUs resident, several pCPUs surplus
for busy housekeeping, disable mwait/hlt/pause vmexits to keep in non-root
mode, ~3% redis performance benefit can be observed on Skylake server.
w/o patchset:
VM-EXIT Samples Samples% Time% Min Time Max Time Avg time
EXTERNAL_INTERRUPT4291649.43% 39.30% 0.47us 106.09us 0.71us (
+- 1.09% )
w/ patchset:
VM-EXIT Samples Samples% Time% Min Time Max Time Avg
time
EXTERNAL_INTERRUPT6871 9.29% 2.96% 0.44us57.88us 0.72us (
+- 4.02% )
Cc: Paolo Bonzini
Cc: Radim Krčmář
Cc: Marcelo Tosatti
v4 -> v5:
* update patch description in patch 1/4
* feed latest apic->lapic_timer.expired_tscdeadline to kvm_wait_lapic_expire()
* squash advance timer handling to patch 2/4
v3 -> v4:
* drop the HRTIMER_MODE_ABS_PINNED, add kick after set pending timer
* don't posted inject already-expired timer
v2 -> v3:
* disarming the vmx preemption timer when
posted_interrupt_inject_timer_enabled()
* check kvm_hlt_in_guest instead
v1 -> v2:
* check vcpu_halt_in_guest
* move module parameter from kvm-intel to kvm
* add housekeeping_enabled
* rename apic_timer_expired_pi to kvm_apic_inject_pending_timer_irqs
Wanpeng Li (4):
KVM: LAPIC: Make lapic timer unpinned
KVM: LAPIC: Inject timer interrupt via posted interrupt
KVM: LAPIC: Ignore timer migration when lapic timer is injected by pi
KVM: LAPIC: Don't inject already-expired timer via posted interrupt
arch/x86/kvm/lapic.c| 68 +++--
arch/x86/kvm/lapic.h| 3 +-
arch/x86/kvm/svm.c | 2 +-
arch/x86/kvm/vmx/vmx.c | 5 +--
arch/x86/kvm/x86.c | 11 ---
arch/x86/kvm/x86.h | 2 ++
include/linux/sched/isolation.h | 2 ++
kernel/sched/isolation.c| 6
8 files changed, 67 insertions(+), 32 deletions(-)
--
2.7.4
