[Samba] aio settings for samba 4.3

[Achim Gottinger]

Am 21.07.2016 um 19:23 schrieb Russell R Poyner:
> 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.
>
> Thanks again
> RP
>
> On 07/20/2016 03:58 AM, Volker Lendecke wrote:
>> On Tue, Jul 19, 2016 at 12:42:53PM -0700, 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.
>> The main reason for our user-space threaded approach is lack of aio in
>> Linux. Proper kernel support for posix AIO might be faster than our
>> implementation. "vfs objects = aio_posix" will give you that.
>>
>> This needs very thorough performance testing. If it turns out to be
>> faster than our threaded aio on FreeBSD, we might have to revive
>> the aio_posix module, it went away last year.
>>
>> Volker
>
>
I think you must tune zfs on freebsd and assume you used an different fs 
for the centos test.