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Message-ID: <wp3aivxpmw.fsf@heho.snv.jussieu.fr>
Date: 17 Oct 2008 16:28:07 +0200
From: "Arno J. Klaassen" <arno@...o.snv.jussieu.fr>
To: Rick Jones <rick.jones2@...com>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: netdev@...r.kernel.org, bugme-daemon@...zilla.kernel.org,
arno@...o.snv.jussieu.fr, Ayaz Abdulla <aabdulla@...dia.com>
Subject: Re: [Bugme-new] [Bug 11752] New: Extremely low netperf UDP_RR throughput for nvidia MCP65
Hello all,
thanx for your help.
Rick Jones <rick.jones2@...com> writes:
> Andrew Morton wrote:
> > (switched to email. Please respond via emailed reply-to-all, not via the
> > bugzilla web interface).
> > On Mon, 13 Oct 2008 13:41:19 -0700 (PDT)
> > bugme-daemon@...zilla.kernel.org wrote:
> >
> >>http://bugzilla.kernel.org/show_bug.cgi?id=11752
> >>
> >> Summary: Extremely low netperf UDP_RR throughput for nvidia MCP65
> >> Product: Drivers
> >> Version: 2.5
> >> KernelVersion: from F10-Beta-x86_64-Live-KDE.iso
> >> Platform: All
> >> OS/Version: Linux
> >> Tree: Mainline
> >> Status: NEW
> >> Severity: normal
> >> Priority: P1
> >> Component: Network
> >> AssignedTo: jgarzik@...ox.com
> >> ReportedBy: arno@...o.snv.jussieu.fr
> >>
> >>
> >>Latest working kernel version: -
> >>Earliest failing kernel version:
> >>Distribution: F10-Beta-x86_64
> >>Hardware Environment: HP Pavillon dv6820ef
> >>Software Environment:
> >>Problem Description: when running at 1Gbps netperf shows good performance for
> >>TCP_STREAM and UDP_STREAM tests, but extremely bad performance for UDP_RR test
> >>(less then 1 ping-pong a second whereas at 100Mbps performance easily reaches
> >>10-20K a second)
> >>
> >>A friend figured out that it looks like small packets at 1Gbps are dropped
> >>as being falsely considered crc-errored.
>
> Given how netperf UDP_RR has _no_ recovery from lost datagrams, it
> makes sense that performance on that test would be very low - the
> first lost datagram the transactions come to a screeching halt until
> the end-of-test timer expires.
>
> Are netstat stats showing retransmissions during a TCP_STREAM test?
I will check that later tonoght and/or this WE
> How about a TCP_RR test? TCP_RR might be low too, it just wouldn't
> necessarily be as low since TCP will get things started again after a
> loss. UDP_STREAM would just go blasting along without a care in the
> world...
A summary of all tests is (REFERENCE being a freebsd6 box on same
LAN against same server running netserver; it's pretty clear that
the *STREAM tests perform OK and the *RR test poor to very poor) :
TCP_STREAM
Throughput
10^6bits/sec
REFERENCE 349.57
fc10-x64 138.48
UDP_STREAM
Throughput
10^6bits/sec
REFERENCE 388.45
fc10-x64 365.10
TCP_RR
Trans.
Rate
per sec
REFERENCE 9801.58
fc10-x64 86.87
TCP_CRR
Trans.
Rate
per sec
REFERENCE 4520.98
fc10-x64 5.60
UDP_RR
Trans.
Rate
per sec
REFERENCE 9473.20
fc10-x64 0.80
Arno
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