[RndTbl] NIC performance with iperf
john at johnlange.ca
john at johnlange.ca
Sat Apr 17 22:28:22 CDT 2010
Isn't Windows still running a BSD decendent IP stack?
Just thought I'd troll a little ;)
John
Sent from my BlackBerry device on the Rogers Wireless Network
-----Original Message-----
From: "Adam Thompson" <athompso at athompso.net>
Date: Sat, 17 Apr 2010 14:34:39
To: 'Continuation of Round Table discussion'<roundtable at muug.mb.ca>
Subject: Re: [RndTbl] NIC performance with iperf
> I installed a cheap GigE switch for a customer using 2006-era P4 Dell
> desktops,
> running XP with cheap Broadcom GigE NICs. Constant 600-700mbit for
> file
> transfers.
> CPU I think was ~30%, but that may have included the AV scanning the
> file.
>
> I assumed Iperf is developed/optimized natively under *NIX and the
> Windows
> version is compiled under Cygwin, do you have any indication that it's
> optimized?
I'm certain iperf is NOT optimized for Windows. However, empirically I
can determine using application-level tests (i.e. FTP, SAMBA, etc.) that
the numbers I'm seeing are consistent.
Worth mentioning is that Microsoft shipped "ttcp.exe" on most versions of
Windows XP install media, under VALUEADD\NET\something, IIRC. Presumably
that binary is reasonably-well optimized. I recall using it to test
between Windows XP and Solaris, and seeing half-decent speeds but nothing
wonderful (~400Mbps).
Equally, I know that I too, have seen lesser Windows clients talking to
Windows servers at higher speeds. It's also worth noting that SMB traffic
to my Linux box is noticeably slower than it was to the Sun Ultra
Enterprise 450 it replaced. While there's obviously something wrong with
the networking stack on my Windows 7 PC (100% CPU utilization just to do
TCP?!) it's also possible that there's some specific interaction between
the Linux and Windows stacks.
As I demonstrated, Linux-to-linux works great. Kevin demonstrated that
MacOSX-Linux works great. Many of us have anecdotal evidence that
Windows-Windows works well, and several people have recently demonstrated
that Windows-Linux does NOT work well. And I've personally demonstrated
(although I haven't posted any numbers here) that Windows-Solaris (*not*
OpenSolaris, if it makes any difference) works better than Windows-Linux.
(OK, I engaged in a bit of Windows-bashing when I blamed the Windows
networking stack *exclusively*.)
I don't have any desire to set up a test lab in my living room just to try
out the various combinations... how much effect can the GigE switch have
on performance? I'm using dirt-cheap D-Link 5-port switches if that makes
any difference.
-Adam Thompson
<athompso at athompso.net>
(204) 291-7950
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