Re: [Qemu-devel] [PATCH v7 RFC] block/vxhs: Initial commit to add Veritas HyperScale VxHS block device support

[Stefan Hajnoczi]

On Thu, Oct 20, 2016 at 01:31:15AM +0000, Ketan Nilangekar wrote:
> 2. The idea of having multi-threaded epoll based network client was to drive 
> more throughput by using multiplexed epoll implementation and (fairly) 
> distributing IOs from several vdisks (typical VM assumed to have atleast 2) 
> across 8 connections. 
> Each connection is serviced by single epoll and does not share its context 
> with other connections/epoll. All memory pools/queues are in the context of a 
> connection/epoll.
> The qemu thread enqueues IO request in one of the 8 epoll queues using a 
> round-robin. Responses are also handled in the context of an epoll loop and 
> do not share context with other epolls. Any synchronization code that you see 
> today in the driver callback is code that handles the split IOs which we plan 
> to address by a) implementing readv in libqnio and b) removing the 4MB limit 
> on write IO size.
> The number of client epoll threads (8) is a #define in qnio and can easily be 
> changed. However our tests indicate that we are able to drive a good number 
> of IOs using 8 threads/epolls.
> I am sure there are ways to simplify the library implementation, but for now 
> the performance of the epoll threads is more than satisfactory.

Have you benchmarked against just 1 epoll thread with 8 connections?

Stefan

signature.asc
Description: PGP signature