[Samba] Inconsistent performance (4.1.6)

[gabe mart]

>>    socket options = IPTOS_LOWDELAY TCP_NODELAY SO_RCVBUF=131072
>> SO_SNDBUF=131072

>Remove the above. It's pure voodoo and hasn't
>been needed for many many years with modern kernels.

After removing the options, the performance dropped on my "good" machines
from 80 MB/s to ~37 MB/s on reads and ~57 MB/s on writes.  On my "bad"
machines this had no effect.

>>    aio read size = 16384
>>    aio write size = 16384
>>    write cache size = 268435456

>>    min receivefile size = 16384

> I get the feeling you're just adding 'performance'
> options here without understanding what they do.
> Especially 'write cache size' :-).

> Remove all the above and re-benchmark. Add them
> in, one by one after reading the man pages *carefully*.

> aio read/write isn't much use without the aio_pthread
> module for example.


I must be mistaken, but aio read/write is supported by default on the
compile:

  --with-aio-support
            Build with aio-support support (default=yes)

Also, write cache size was input after considering the amount of cache my
RAID controllers have and deciding on the number specified.  Although it
didn't seem to improve performance, it did not hurt, so I left it in.  I
realize that 'min receivefile size' is used for unsigned connections and I
was hoping (at one point during testing) that I could achieve some level of
performance on my "bad" machines with unsigned connections.  This test
failed and I had not cleaned up the config file.

Adding back in the socket options without the aio lines read performance
goes to ~55 and write to ~40 and no affect on the "bad" machines.

Any way to rule out the performance being the samba server?