9p: requests efficiency

[Christian Schoenebeck]

I'm currently reading up on how client requests (T messages) are currently 
dispatched in general by 9pfs, to understand where potential inefficiencies 
are that I am encountering.

I mean 9pfs is pretty fast on raw I/O (read/write requests), provided that the 
message payload on guest side was chosen large enough (e.g. 
trans=virtio,version=9p2000.L,msize=4194304,...), where I already come close 
to my test disk's therotical maximum performance on read/write tests. But 
obviously these are huge 9p requests.

However when there are a large number of (i.e. small) 9p requests, no matter 
what the actual request type is, then I am encountering severe performance 
issues with 9pfs and I try to understand whether this could be improved with 
reasonable effort.

If I understand it correctly, each incoming request (T message) is dispatched 
to its own qemu coroutine queue. So individual requests should already be 
processed in parallel, right?

Best regards,
Christian Schoenebeck