[Samba] aio settings for samba 4.3

[Russell R Poyner]

Jeremy,

I re-built the samba43 port with aio_support unset and pthreadpool set.

smbd -b|grep aio
vfs_aio_fork_init
vfs_aio_pthread_init

from smb4.conf:

oplocks = yes
kernel oplocks = no
smb2 leases = yes
server min protocol = smb2

aio read size = 1024
aio write size = 1024
vfs objects = aio_pthread


The new build gives pretty much the same speeds as before using MS 
diskspd under windows 7. Around 15MB/s for a random workload with 4k 
blocks. Up to about 25MB/s with 64k blocks. For comparison I ran diskspd 
on the windows 7 box using a windows 8 machine as the server. The 
results were 49MB/s for 4k blocks and 1787MB/s for 64k blocks. Clearly 
1787 MB/s is more than wire speed and reflects a cache effect that samba 
doesn't access.

With the new build I do see smbd spawning extra threads under load. They 
just don't seem to add any performance benefit.

This is a freebsd 10.2 system with samba running inside a jail.

Thanks again
Russ poyner

On 07/19/2016 02:42 PM, Jeremy Allison wrote:
> On Tue, Jul 19, 2016 at 12:49:09PM -0500, Russell R Poyner wrote:
>> 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
> You don't need these, modern Samba includes a pthread pool
> implementation that will parallelize SMB io requests.
>
> Ensure the clients are using SMB2 and SMB2 leases are
> enabled. You should be able to get close to wirespeed.