Re: [RESEND] memory: avoid updating ioeventfds for some address_space

[Peter Xu]

Hongmianquan,

On Tue, Aug 29, 2023 at 10:23:54AM +0800, hongmianquan wrote:
> When updating ioeventfds, we need to iterate all address spaces,
> but some address spaces do not register eventfd_add|del call when
> memory_listener_register() and they do nothing when updating ioeventfds.
> So we can skip these AS in address_space_update_ioeventfds().
> 
> The overhead of memory_region_transaction_commit() can be significantly
> reduced. For example, a VM with 8 vhost net devices and each one has
> 64 vectors, can reduce the time spent on memory_region_transaction_commit by 
> 20%.
> 
> Signed-off-by: hongmianquan <hongmianquan@bytedance.com>

Please feel free to take my R-b with the patch if the patch didn't change.

Thanks,

-- 
Peter Xu