netdev - Re: [Bugme-new] [Bug 11752] New: Extremely low netperf UDP

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Message-ID: <wp4p2s9alp.fsf@heho.snv.jussieu.fr>
Date:	31 Oct 2008 14:07:30 +0100
From:	"Arno J. Klaassen" <arno@...o.snv.jussieu.fr>
To:	Rick Jones <rick.jones2@...com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, netdev@...r.kernel.org,
	bugme-daemon@...zilla.kernel.org,
	Ayaz Abdulla <aabdulla@...dia.com>
Subject: Re: [Bugme-new] [Bug 11752] New: Extremely low	netperf	UDP_RR	throughput for nvidia MCP65


Hello,


sorry for the late response

Rick Jones <rick.jones2@...com> writes:

> >>Clearly something is fubar with the rx side (well duh :).  The next
> >>set of stats I'd try to look at would be ethtool stats for the
> >>interface, eg ethtool -S eth0 and see if it shows someting more
> >>specific for the "RX-ERR" shown by netstat -I eth0.
> > OK, here it is (rx_errors_total: 10049, rx_crc_errors: 10049) :
> 
> Well, that seems to confirm that it is CRC errors.  Did your friend
> say why he thought they were false CRC errors?

nope, but he gave me a patch for the freebsd driver which [would] "try
to pass CRC errored frames to upper stack."
 
And it improved the *RR tests by an order of magnitude (still leaving
them another order of magnitude below reference values)

> If indeed it is only small packets/frames getting the CRC errors, in
> _theory_ a TCP_RR test with a larger request/response size should show
> "good" performance because there should be few if any standalone
> ACKs. You could start with something like:
> 
> netperf -H <remote> -t TCP_RR -- -r 1448
> 
> and work your way down, checking for those CRC errors as you go.  I
> don't thnik folks need all the output, just some idea of if you still
> see CRC errors with full-size TCP_RR and if you don't at what size you
> start to see them.  I picked 1448 to have the request and response
> both result in a "full" TCP segment assuming an MTU of 1500 bytes and
> timestamps being enabled. (net.ipv4.tcp_timestamps).


packet/frame size does not seem to be of any influence; I tried
a bunch of combinations and all give more or less the same performance


> Has the usual litany of cable swapping and such been done already?  A
> cable *known* to be good at 1G swapped-in and such?  If this is via a
> switch, just for completeness trying other switch ports etc etc.


yop; I tested with 3 differents switches and a couple of different
cables, including the famous *known* good one as well as a brand
new one; no difference
 
> While I'd not expect it to be at 1Gig and autoneg, CRC errors can
> sometimes be a sign of a duplex mismatch, but I have a difficult time
> seeing that happening - unless there happens to be other traffic on
> the link a plain netperf TCP_RR or UDP_RR test should "never" have
> both sides trying to talk at the same time and so shouldn't trip-over
> a duplex mismatch like a TCP_STREAM test would.
> 
> > (NB, let me know how to eventually test eventual patches/binary
> > modules on a life-CD; I've just limited linux kernel skills)
> 
> I'm going to have to defer to others on that score.  Meanwhile some
> additional information gathering:
> 
> For grins and bugzilla posterity, ethtool -i <interface> would be
> goodness. 

[root@...alhost mcp65]# ethtool -i eth0
driver: forcedeth                      
version: 0.61                          
firmware-version:                      
bus-info: 0000:00:06.0        

> What was the last "known good" configuration?  What is
> running "on the other side?" etc etc.  Does say some other or earlier
> distro (Fedora, Ubuntu whatnot) Live CD not exhibit this problem?  If
> not, what are the kernel and ethtool -i information from that?


I have this problem since I bought this notebook a month ago.

I tried freebsd7 (nfe driver), opensolaris5.10 (nfo driver) and fc10
all with same result.
It also runs vista, but I cannot find a netperf.exe for 2.4.4 ...
if someone has a pointer (I found an earlier version but it
makes netserver core dump when startiong the test)

thanx for your help
> rick jones


Arno

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