diff options
| author | Christian Borntraeger <borntraeger@de.ibm.com> | 2009-05-12 17:21:49 +0200 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2009-06-10 11:48:55 +0300 |
| commit | ca8723023f25c9a70d76cbd6101f8fb4ffec2fa0 (patch) | |
| tree | ef753d244a55271279b5b2cf29b28db5b35b454c /arch/s390/kvm/interrupt.c | |
| parent | 2668dab794272f0898491acaf1e77e9a005abc0f (diff) | |
KVM: s390: use hrtimer for clock wakeup from idle - v2
This patch reworks the s390 clock comparator wakeup to hrtimer. The clock
comparator is a per-cpu value that is compared against the TOD clock. If
ckc <= TOD an external interrupt 1004 is triggered. Since the clock comparator
and the TOD clock have a much higher resolution than jiffies we should use
hrtimers to trigger the wakeup. This speeds up guest nanosleep for small
values.
Since hrtimers callbacks run in hard-irq context, I added a tasklet to do
the actual work with enabled interrupts.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Christian Ehrhardt <ehrhardt@de.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/s390/kvm/interrupt.c')
| -rw-r--r-- | arch/s390/kvm/interrupt.c | 33 |
1 files changed, 23 insertions, 10 deletions
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c index 4ed4c3a1148..a48830fa9c5 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -12,6 +12,8 @@ #include <asm/lowcore.h> #include <asm/uaccess.h> +#include <linux/hrtimer.h> +#include <linux/interrupt.h> #include <linux/kvm_host.h> #include <linux/signal.h> #include "kvm-s390.h" @@ -361,12 +363,10 @@ int kvm_s390_handle_wait(struct kvm_vcpu *vcpu) return 0; } - sltime = (vcpu->arch.sie_block->ckc - now) / (0xf4240000ul / HZ) + 1; + sltime = ((vcpu->arch.sie_block->ckc - now)*125)>>9; - vcpu->arch.ckc_timer.expires = jiffies + sltime; - - add_timer(&vcpu->arch.ckc_timer); - VCPU_EVENT(vcpu, 5, "enabled wait timer:%llx jiffies", sltime); + hrtimer_start(&vcpu->arch.ckc_timer, ktime_set (0, sltime) , HRTIMER_MODE_REL); + VCPU_EVENT(vcpu, 5, "enabled wait via clock comparator: %llx ns", sltime); no_timer: spin_lock_bh(&vcpu->arch.local_int.float_int->lock); spin_lock_bh(&vcpu->arch.local_int.lock); @@ -389,21 +389,34 @@ no_timer: remove_wait_queue(&vcpu->wq, &wait); spin_unlock_bh(&vcpu->arch.local_int.lock); spin_unlock_bh(&vcpu->arch.local_int.float_int->lock); - del_timer(&vcpu->arch.ckc_timer); + hrtimer_try_to_cancel(&vcpu->arch.ckc_timer); return 0; } -void kvm_s390_idle_wakeup(unsigned long data) +void kvm_s390_tasklet(unsigned long parm) { - struct kvm_vcpu *vcpu = (struct kvm_vcpu *)data; + struct kvm_vcpu *vcpu = (struct kvm_vcpu *) parm; - spin_lock_bh(&vcpu->arch.local_int.lock); + spin_lock(&vcpu->arch.local_int.lock); vcpu->arch.local_int.timer_due = 1; if (waitqueue_active(&vcpu->arch.local_int.wq)) wake_up_interruptible(&vcpu->arch.local_int.wq); - spin_unlock_bh(&vcpu->arch.local_int.lock); + spin_unlock(&vcpu->arch.local_int.lock); } +/* + * low level hrtimer wake routine. Because this runs in hardirq context + * we schedule a tasklet to do the real work. + */ +enum hrtimer_restart kvm_s390_idle_wakeup(struct hrtimer *timer) +{ + struct kvm_vcpu *vcpu; + + vcpu = container_of(timer, struct kvm_vcpu, arch.ckc_timer); + tasklet_schedule(&vcpu->arch.tasklet); + + return HRTIMER_NORESTART; +} void kvm_s390_deliver_pending_interrupts(struct kvm_vcpu *vcpu) { |