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Re: BCM5704 performance questions.

To: "David S. Miller" <davem@xxxxxxxxxxxxx>
Subject: Re: BCM5704 performance questions.
From: Ben Greear <greearb@xxxxxxxxxxxxxxx>
Date: Thu, 09 Jun 2005 19:28:47 -0700
Cc: netdev@xxxxxxxxxxx, mchan@xxxxxxxxxxxx
In-reply-to: <20050609.182943.29573731.davem@davemloft.net>
Organization: Candela Technologies
References: <42A8E0FE.3020708@candelatech.com> <20050609.175417.108740435.davem@davemloft.net> <42A8EAE1.5030201@candelatech.com> <20050609.182943.29573731.davem@davemloft.net>
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David S. Miller wrote:
From: Ben Greear <greearb@xxxxxxxxxxxxxxx>
Date: Thu, 09 Jun 2005 18:20:33 -0700


I ran a test using pktgen to (try to) send 82kpps, 1514 byte packets between
two ports on the tg3 NIC.  It can do about 780Mbps in one direction,
and 880Mbps in the other direction.  Lots of harmless hard-start xmit errors 
reported
(tg3 may not stop it's tx queue correctly, or maybe pktgen is screwed up since
e1000 reports similar errors).


There is a known race on SMP with drivers using NETIF_F_LLTX that is
still not fixed.  It will cause the error message to be reported from
the driver's ->hard_start_xmit() routine when you hit this race.

Ok, it's not a big deal, since I can just retry the packet when the tx queue wakes up again. The message was coming from pktgen, btw.

You're definitely on an SMP system if you are triggering that message.

Yes, dual xeon with HT as well.


Thanks, Ben

--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc  http://www.candelatech.com


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