On 08/13/2012 01:16 PM, Gleb Natapov wrote:
> On Mon, Aug 13, 2012 at 01:12:46PM +0300, Michael S. Tsirkin wrote:
>> On Mon, Aug 13, 2012 at 12:36:41PM +0300, Avi Kivity wrote:
>> > On 08/13/2012 12:16 PM, Gleb Natapov wrote:
>> > > Here is a quick prototype of what we discussed yesterday. This one
>> > > caches only MSI interrupts for now. The obvious problem is that not
>> > > all interrupts (namely IPIs and MSIs using KVM_CAP_SIGNAL_MSI) use irq
>> > > routing table, so they cannot be cached.
>> > 
>> > We can have a small rcu-managed hash table to look those up.
>> 
>> Yes but how small? We probably need at least one entry
>> per vcpu, no?
>> 
> One entry? We will spend more time managing it than injecting interrupts
> :) ideally we need entry for each IPI sent and for each potential MSI
> from userspace. What happens when hash table is full? 

Drop the entire cache.

> We stop caching or
> invalidate old entries? If later then cache can go valid->invalid which
> may complicate the code.
> 

We can drop the entire cache via rcu freeing.  In fact we can have a
closed hash allocated as a single blob, easy to manage.

-- 
error compiling committee.c: too many arguments to function
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