Messages in this thread |  | | | Date | Thu, 16 Sep 2010 12:20:47 +0200 | | From | Gleb Natapov <> | | Subject | Re: [PATCH RFC] kvm: enable irq injection from interrupt context |
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On Thu, Sep 16, 2010 at 12:13:39PM +0200, Michael S. Tsirkin wrote: > On Thu, Sep 16, 2010 at 12:13:32PM +0200, Gleb Natapov wrote: > > On Thu, Sep 16, 2010 at 11:53:10AM +0200, Michael S. Tsirkin wrote: > > > On Thu, Sep 16, 2010 at 11:46:03AM +0200, Avi Kivity wrote: > > > > On 09/16/2010 11:25 AM, Gleb Natapov wrote: > > > > >> > > > > >> MSI only appeared in rhel6, older guests still use level interrupts. > > > > >So they are already slow for other reasons. > > > > > > > > > > > > > Exactly, for example they need to exit to userspace to ack the > > > > interrupt. That's far slower than the workqueue. > > > > > > Well, this is not exactly comparable: you might get > > > same irq asserted multiple times and only deasserted once. > > > > > Are we talking about level interrupts? Why would you assert level > > triggered interrupt multiple times before deasserting it? > > User of irqfd has no way to know what current interrupt level is. > So it has to keep asserting. > Why can't it keep track of current level?
-- Gleb.
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