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SubjectRe: [PATCH] kvm: fast-path msi injection with irqfd
>>> On 11/19/2010 at 10:54 AM, in message <20101119155427.GA20279@amt.cnet>,
Marcelo Tosatti <> wrote:
> On Thu, Nov 18, 2010 at 07:09:08PM +0200, Michael S. Tsirkin wrote:
>> Store irq routing table pointer in the irqfd object,
>> and use that to inject MSI directly without bouncing out to
>> a kernel thread.
>> While we touch this structure, rearrange irqfd fields to make fastpath
>> better packed for better cache utilization.
>> This also adds some comments about locking rules and rcu usage in code.
>> Some notes on the design:
>> - Use pointer into the rt instead of copying an entry,
>> to make it possible to use rcu, thus side-stepping
>> locking complexities. We also save some memory this way.
>> - Old workqueue code is still used for level irqs.
>> I don't think we DTRT with level anyway, however,
>> it seems easier to keep the code around as
>> it has been thought through and debugged, and fix level later than
>> rip out and re-instate it later.
>> Signed-off-by: Michael S. Tsirkin <>
>> ---
>> OK, this seems to work fine for me. Tested with virtio-net in guest
>> with and without vhost-net. Pls review/apply if appropriate.
> Acked-by: Marcelo Tosatti <>

Acked-by: Gregory Haskins <>

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