On 01/06/2010 01:44 PM, Gleb Natapov wrote:
On Wed, Jan 06, 2010 at 01:23:28PM -0600, Anthony Liguori wrote:
On 01/06/2010 01:20 PM, Beth Kon wrote:
Beth Kon wrote:
I will try to look into this. Since HPET is edge-triggered,
looks like this problem is of a different nature than PIT. Is
this a solid failure or intermittent?
Anthony just explained that on x86, even edge-triggered interrupts
are queued in the apic and an eoi will occur, so this is not
different than the PIT.
Not quite queued in the sense that multiple events will be delivered
in order, but I think the point is that you can still detect whether
delivery succeeded by counting APIC EOIs.
The trouble is that historically we've struggled with doing this in
userspace. Maybe it's time to revisit.
We reinject PIT interrupts from kernel and RTC interrupts from
userspace.
Because we can determine that we've missed an RTC interrupt in
userspace. We cannot determine this with the PIT without adding a hook
into the userspace apic that lets us know whether an injection failed or
not.
Regards,
Anthony Liguori
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