[Performance] Samba 3 vs. Samba 4 performance in NetBench

[Andrew Tridgell]

Marc,

 > I should note that the reason I did the oplock on vs. oplock off tests
 > in Samba 3 is that tridge pointed out to me that Samba 4 doesn't have
 > oplock support yet. As you can see oplocks provide a huge performance
 > bump in the Samba 3 tests, and the oplock off test provides a good
 > baseline to compare Samba 4 against.

yes, its interesting what a difference the oplocks make, although as I
suspect when you first showed me the results, they don't explain all
of the difference.

I'd like to get to the bottom of the remaining difference. As I've
mentioned to you, my own tests using BENCH-NBENCH, which is supposed
to be a simulation of NetBench, show Samba4 doing better by about as
much as you results show Samba3 doing better! I'd be keen to see
BENCH-NBENCH results for your setup if you can do them. Unfortunately
I can't run a true NetBench run here as I don't have the necessary
hardware.

I did think of one possible explanation this morning. Samba4 and
Samba3 negotiate different buffer sizes. Could that explain such a big
difference? I'd be surprised if it can, but it might be worth looking
at. 

The good news is that you see the difference even with a single
client. That should make it possible to analyse the difference by
comparing a sniff of the two situations (with oplocks off). If you
keep the runtime as short as you can while still having a clear
difference then the sniff should be small enough for you to put up
somewhere for download. That will allow us to see exactly which calls
are faster/slower, and whether there is any difference in what calls
are made, and what parameters are used for those calls.

btw, I think NetBench can produce output showing the latency of each
category of call. Do you have that info? It doesn't seem to be in the
spreadsheet you sent.

Cheers, Tridge