NFS server bottlenecks

[Nikolay Denev]

On Oct 20, 2012, at 3:11 PM, Ivan Voras <ivoras at freebsd.org> wrote:

> On 20 October 2012 13:42, Nikolay Denev <ndenev at gmail.com> wrote:
> 
>> Here are the results from testing both patches : http://home.totalterror.net/freebsd/nfstest/results.html
>> Both tests ran for about 14 hours ( a bit too much, but I wanted to compare different zfs recordsize settings ),
>> and were done first after a fresh reboot.
>> The only noticeable difference seems to be much more context switches with Ivan's patch.
> 
> Thank you very much for your extensive testing!
> 
> I don't know how to interpret the rise in context switches; as this is
> kernel code, I'd expect no context switches. I hope someone else can
> explain.
> 
> But, you have also shown that my patch doesn't do any better than
> Rick's even on a fairly large configuration, so I don't think there's
> value in adding the extra complexity, and Rick knows NFS much better
> than I do.
> 
> But there are a few things other than that I'm interested in: like why
> does your load average spike almost to 20-ties, and how come that with
> 24 drives in RAID-10 you only push through 600 MBit/s through the 10
> GBit/s Ethernet. Have you tested your drive setup locally (AESNI
> shouldn't be a bottleneck, you should be able to encrypt well into
> Gbyte/s range) and the network?
> 
> If you have the time, could you repeat the tests but with a recent
> Samba server and a CIFS mount on the client side? This is probably not
> important, but I'm just curious of how would it perform on your
> machine.

The first iozone local run finished, I'll paste just the result here, and also the same test over NFS for comparison:
(This is iozone doing 8k sized IO ops, on ZFS dataset with recordsize=8k)

NFS:
                                                            random  random    bkwd   record   stride                                   
              KB  reclen   write rewrite    read    reread    read   write    read  rewrite     read                                   
        33554432       8    4973    5522     2930     2906    2908    3886                                          

Local:
                                                            random  random    bkwd   record   stride                                   
              KB  reclen   write rewrite    read    reread    read   write    read  rewrite     read                                   
        33554432       8   34740   41390   135442   142534   24992   12493                                          


P.S.: I forgot to mention that the network is with 9K mtu.