[Samba] Performance with XP64

Jeremy Allison jra at samba.org
Tue Mar 15 14:56:48 MDT 2011

On Tue, Mar 15, 2011 at 04:35:32PM -0400, Glenn Maynard wrote:
> On Tue, Mar 15, 2011 at 3:36 PM, Volker Lendecke
> <Volker.Lendecke at sernet.de>wrote:
> > On Tue, Mar 15, 2011 at 02:28:37PM -0400, Glenn Maynard wrote:
> > > tcpdump reading a 256MB file (from tmpfs) on XP64:
> > > http://zewt.org/~glenn/samba.tcpdump.gz, 56M/sec
> >
> > That's pretty much what you would expect. The trace shows
> > that your program reads sequentially in 61k chunks. Given
> >
> My program reads in 1M chunks; it's the OS splitting apart the reads.
> that your network latency is roughly 600 microseconds,
> > ftp://pserver.samba.org/pub/unpacked/junkcode/expected_throughput.pl
> >
> gives 55MB/sec. You might want to try smbclient, that does
> > larger parallel reads, or a copy program that uses multiple
> > threads simultaneously.
> >
> That's what I'd expect if things are as broken as they look from that dump:
> the client (XP) isn't buffering requests at all, so the window caps out at
> 64k.  The mail from earlier[1] suggests that some people get much better
> speed from other servers (though without enough information to really be
> useful).  I don't know the protocol, so I can't tell if there's something
> preventing the client from buffering multiple read requests, for example,
> which I'd expect of any network FS.
> Multiple threads isn't a good solution (at these speeds, it's liable to
> severely hurt streaming performance), and in any case it doesn't help actual
> use, with real applications.

Well having multiple threads on the client side seems to allow
multiple simultaneous outstanding requests, which is what I think
the Intel NAS test does.


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