[Samba] aio settings for samba 4.3

[Russell R Poyner]

I'm tuning a samba 4.3 install on freebsd and I'm confused about aio 
settings.

I've loaded the freebsd aio kernel module and tried various values or 
aio read size and aio write size, but it seems to make no difference in 
the speed.

Using MS diskspd against a samba share from a fast zfs pool I get 
something like 25MB/s tops. That's well below the capacity of my Gb 
network and my disk system. FWIW iperf shows >900Mbits/sec in both 
directions on the link.

# smbd -b|grep aio
    vfs_aio_fork_init
    vfs_aio_posix_init
    vfs_aio_pthread_init

As always google finds lots of tuning advice, but it's not clear what if 
any of it applies to 4.3 on FreeBSD.

Thanks
Russ Poyner