[Bug 8512] rsync is slower than cp -- Reduce overhead to cp for transfer of large files

[samba-bugs at samba.org]

https://bugzilla.samba.org/show_bug.cgi?id=8512

--- Comment #4 from John Wiegley <johnw at newartisans.com> 2013-11-17 09:02:51 UTC ---
Let me add my voice to the mix here.  I'm copying a 1GB VOB file from an Ubuntu
ZFS server running Samba 4.1.1, to my Mac OS X 10.9 box.

iperf reports 112 MB/s (should be my theoretical maximum).
Copying with Path Finder over Samba: 99 MB/s.
Copying with rsync directly (using arcfour256): 92 MB/s.
Copying with dd over Samba: 67 MB/s.
Copying with cat over Samba (measured with pv): 69 MB/s.
Copying with rsync over Samba: 55 MB/s.

I'm using gigabit ethernet, obviously, with mtu set to 1500 and no TCP options
other than the following in smb.conf:

    socket options = TCP_NODELAY SO_RCVBUF=131072 SO_SNDBUF=131072

These numbers are very stable over several runs, so I'm pretty curious now
about what's going on, especially with rsync.

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