On 10/04/2010 03:04 AM, Avi Kivity wrote:
On 10/04/2010 03:18 AM, Anthony Liguori wrote:
On 10/03/2010 09:28 AM, Michael S. Tsirkin wrote:
This is using eventfd as well.
Sorry, I meant irqfd.
I've tried using irqfd in userspace. It hurts performance quite a
bit compared to doing an ioctl so I would suspect this too.
A last_used_idx or similar mechanism should help performance quite a
bit on top of ioeventfd too.
Any idea why? While irqfd does quite a bit of extra locking, it
shouldn't be that bad.
Not really. It was somewhat counter intuitive.
A worthwhile experiment might be to do some layering violations and have
vhost do an irq injection via an ioctl and see what the performance
delta is. I suspect it could give vhost a nice boost.
Regards,
Anthony Liguori
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