[Samba] aio settings for samba 4.3

[Jeremy Allison]

On Thu, Jul 21, 2016 at 12:23:01PM -0500, Russell R Poyner wrote:
> One more data point for comparison
> 
> I installed the stock samba 4.2 rpm on a centos 7 machine and ran
> the same diskspd tests against a share configured with:
>    vfs objects = aio_pthread
>    aio read size = 1024
>    aio read size = 1024
> 
>    smb2 leases = yes
> 
> I get 27MB/s with 4k blocks and 145MB/s with 64k blocks. Disabling
> cacheing by passing the -h switch to diskspd lowered these to 72MB/s
> and 11MB/s. Which I view as 'close enough' to wire speed. Thus it
> seems that the dismal performance I see is associated with the
> FreeBSD implementation somehow.

That's interesting, but I'm afraid I don't know FreeBSD well
enough to help here. This does imply the problem isn't Samba
specific though (unless it's a complex interaction between
Samba+FreeBSD).