On Wed, Jul 15, 2009 at 06:42:05PM -0300, Marcelo Tosatti wrote:
> On Wed, Jul 15, 2009 at 11:52:24PM +0300, Gleb Natapov wrote:
> > On Wed, Jul 15, 2009 at 03:18:00PM -0300, Marcelo Tosatti wrote:
> > > On Tue, Jul 14, 2009 at 05:30:45PM +0300, Gleb Natapov wrote:
> > > > Use gsi indexed array instead of scanning all entries on each interrupt
> > > > injection. Also maintain back mapping from irqchip/pin to gsi to speedup
> > > > interrupt acknowledgment notifications.
> > > >
> > > > Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
> > > > ---
> > > > include/linux/kvm_host.h | 11 ++++++-
> > > > virt/kvm/irq_comm.c | 62 ++++++++++++++++++++++++++++-----------------
> > > > 2 files changed, 47 insertions(+), 26 deletions(-)
> > > >
> > > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> > > > index aa64d0d..ae6cbf1 100644
> > > > --- a/include/linux/kvm_host.h
> > > > +++ b/include/linux/kvm_host.h
> > > > @@ -128,7 +128,14 @@ struct kvm_kernel_irq_routing_entry {
> > > > } irqchip;
> > > > struct msi_msg msi;
> > > > };
> > > > - struct list_head link;
> > > > + struct hlist_node link;
> > > > +};
> > > > +
> > > > +struct kvm_irq_routing_table {
> > > > + int chip[3][KVM_IOAPIC_NUM_PINS];
> > > > + struct kvm_kernel_irq_routing_entry *rt_entries;
> > > > + u32 max_gsi;
> > > > + struct hlist_head map[0];
> > > > };
> > > >
> > > > struct kvm {
> > > > @@ -165,7 +172,7 @@ struct kvm {
> > > > #endif
> > > >
> > > > #ifdef CONFIG_HAVE_KVM_IRQCHIP
> > > > - struct kvm_kernel_irq_routing_entry *irq_routing;
> > > > + struct kvm_irq_routing_table *irq_routing;
> > > > spinlock_t irq_routing_lock;
> > > > struct hlist_head mask_notifier_list;
> > > > struct hlist_head irq_ack_notifier_list;
> > > > diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
> > > > index c54a28b..da643d4 100644
> > > > --- a/virt/kvm/irq_comm.c
> > > > +++ b/virt/kvm/irq_comm.c
> > > > @@ -125,6 +125,8 @@ int kvm_set_irq(struct kvm *kvm, int irq_source_id, int irq, int level)
> > > > struct kvm_kernel_irq_routing_entry *e;
> > > > unsigned long *irq_state, sig_level;
> > > > int ret = -1;
> > > > + struct kvm_irq_routing_table *irq_rt;
> > > > + struct hlist_node *n;
> > > >
> > > > trace_kvm_set_irq(irq, level, irq_source_id);
> > > >
> > > > @@ -147,14 +149,13 @@ int kvm_set_irq(struct kvm *kvm, int irq_source_id, int irq, int level)
> > > > * writes to the unused one.
> > > > */
> > > > rcu_read_lock();
> > > > - for (e = rcu_dereference(kvm->irq_routing); e && e->set; e++) {
> > > > - if (e->gsi == irq) {
> > > > - int r = e->set(e, kvm, sig_level);
> > > > - if (r < 0)
> > > > - continue;
> > > > + irq_rt = rcu_dereference(kvm->irq_routing);
> > > > + hlist_for_each_entry(e, n, &irq_rt->map[irq], link) {
> > > > + int r = e->set(e, kvm, sig_level);
> > > > + if (r < 0)
> > > > + continue;
> > > >
> > > > - ret = r + ((ret < 0) ? 0 : ret);
> > > > - }
> > > > + ret = r + ((ret < 0) ? 0 : ret);
> > > > }
> > > > rcu_read_unlock();
> > > > return ret;
> > > > @@ -162,21 +163,16 @@ int kvm_set_irq(struct kvm *kvm, int irq_source_id, int irq, int level)
> > > >
> > > > void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
> > > > {
> > > > - struct kvm_kernel_irq_routing_entry *e;
> > > > struct kvm_irq_ack_notifier *kian;
> > > > struct hlist_node *n;
> > > > - unsigned gsi = pin;
> > > > + unsigned gsi;
> > > >
> > > > trace_kvm_ack_irq(irqchip, pin);
> > > >
> > > > rcu_read_lock();
> > > > - for (e = rcu_dereference(kvm->irq_routing); e && e->set; e++) {
> > > > - if (e->irqchip.irqchip == irqchip &&
> > > > - e->irqchip.pin == pin) {
> > > > - gsi = e->gsi;
> > > > - break;
> > > > - }
> > > > - }
> > > > + gsi = rcu_dereference(kvm->irq_routing)->chip[irqchip][pin];
> > > > + if (gsi == -1)
> > > > + gsi = pin;
> > > >
> > > > hlist_for_each_entry_rcu(kian, n, &kvm->irq_ack_notifier_list, link)
> > > > if (kian->gsi == gsi)
> > > > @@ -277,7 +273,8 @@ void kvm_free_irq_routing(struct kvm *kvm)
> > > > kfree(kvm->irq_routing);
> > > > }
> > > >
> > > > -static int setup_routing_entry(struct kvm_kernel_irq_routing_entry *e,
> > > > +static int setup_routing_entry(struct kvm_irq_routing_table *rt,
> > > > + struct kvm_kernel_irq_routing_entry *e,
> > > > const struct kvm_irq_routing_entry *ue)
> > > > {
> > > > int r = -EINVAL;
> > > > @@ -303,6 +300,7 @@ static int setup_routing_entry(struct kvm_kernel_irq_routing_entry *e,
> > > > }
> > > > e->irqchip.irqchip = ue->u.irqchip.irqchip;
> > > > e->irqchip.pin = ue->u.irqchip.pin + delta;
> > > > + rt->chip[ue->u.irqchip.irqchip][e->irqchip.pin] = ue->gsi;
> > > > break;
> > > > case KVM_IRQ_ROUTING_MSI:
> > > > e->set = kvm_set_msi;
> > > > @@ -313,6 +311,8 @@ static int setup_routing_entry(struct kvm_kernel_irq_routing_entry *e,
> > > > default:
> > > > goto out;
> > > > }
> > > > +
> > > > + hlist_add_head(&e->link, &rt->map[e->gsi]);
> > > > r = 0;
> > > > out:
> > > > return r;
> > > > @@ -324,23 +324,37 @@ int kvm_set_irq_routing(struct kvm *kvm,
> > > > unsigned nr,
> > > > unsigned flags)
> > > > {
> > > > - struct kvm_kernel_irq_routing_entry *new, *old;
> > > > - unsigned i;
> > > > + struct kvm_irq_routing_table *new, *old;
> > > > + u32 i, j, max_gsi = 0;
> > > > int r;
> > > >
> > > > - /* last elemet is left zeored and indicates the end of the array */
> > > > - new = kzalloc(sizeof(*new) * (nr + 1), GFP_KERNEL);
> > > > + for (i = 0; i < nr; ++i) {
> > > > + if (ue[i].gsi >= KVM_MAX_IRQ_ROUTES)
> > > > + return -EINVAL;
> > > > + max_gsi = max(max_gsi, ue[i].gsi);
> > > > + }
> > > > +
> > > > + max_gsi += 1;
> > > > +
> > > > + new = kzalloc(sizeof(*new) + (max_gsi * sizeof(struct hlist_head)) +
> > > > + (nr * sizeof(struct kvm_kernel_irq_routing_entry)),
> > > > + GFP_KERNEL);
> > >
> > > Why don't you allocate the hlist_head's and the routing entries
> > > separately?
> > >
> > I prefer it that way because cleanup after error is much easier. What
> > are the disadvantages?
>
> They are two data structures (two different arrays). Also as mentioned
Logically it is one data structure that includes two arrays and some
other fields.
> before by others the allocation size of irq_routing array might become
> an issue.
>
KVM_MAX_IRQ_ROUTES will be significantly reduced so this will not be the
problem. I plan to reduce it to 128. Will it be OK to use vmalloc() if
the size is greater than one page?
> > > >
> > > > if (!new)
> > > > return -ENOMEM;
> > > >
> > > > + new->rt_entries = (void *)&new->map[max_gsi];
> > > > +
> > > > + new->max_gsi = max_gsi;
> > > > + for (i = 0; i < 3; i++)
> > > > + for (j = 0; j < KVM_IOAPIC_NUM_PINS; j++)
> > > > + new->chip[i][j] = -1;
> > > > +
> > >
> > > Should use something else instead of 3. Maybe dynamic for multiple
> > > IOAPIC's support (but you can argue thats another problem).
> > >
> > This is (another problem). The code has 1 IOAPIC hardcoded pretty deeply
> > even at user/kernel API level. We will solve is some day.
>
> OK
--
Gleb.
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