netdev - Re: intermittant petabyte usage reported with broadcom nic

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Date:	Thu, 12 Apr 2007 16:13:05 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	CaT <cat@....com.au>
Cc:	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	Michael Chan <mchan@...adcom.com>
Subject: Re: intermittant petabyte usage reported with broadcom nic

On Fri, 13 Apr 2007 08:52:49 +1000
CaT <cat@....com.au> wrote:

> On Mon, Apr 02, 2007 at 12:13:00AM -0700, Andrew Morton wrote:
> > On Mon, 2 Apr 2007 11:43:19 +1000 CaT <cat@....com.au> wrote:
> > 
> > > I take minute by minute snapshots of network traffic by sampling
> > > /proc/net/dev and most of the time everything works fine. Occasionally
> > > though I get petabyte byte traffic and corresponding packet traffic.
> > 
> > How frequently?
> > 
> > Are you able to provide some actual numbers (expected and actual values),
> > so we can look at the bit patterns?
> 
> I have some now. These are raw lines from /proc/net/dev. In this case it's
> eth0 at 22:14 that chucked a wee wibbly.
> 
> Apr 11 22:13:02 '  eth0:17227166357 81379716    0    0    0     0          0         0 33090495625 86656584    0    0    0     0       0          0 '
> Apr 11 22:13:02 '  eth1:30708022097 91219466    0    0    0     0          0         0 122989582024 125073786    0    0    0     0       0          0 '
> Apr 11 22:14:02 '  eth0:220898233988841368 66750274    0    0    0     0          0  86458738 52386430545 101089219 199313    0    0     0  199313          0 '

0x310_c9c6_006a_7f98

Not sure what to make of that.

> Apr 11 22:14:02 '  eth1:30708307787 91220183    0    0    0     0          0         0 122989665004 125074344    0    0    0     0       0          0 '
> Apr 11 22:15:02 '  eth0:17227454818 81381144    0    0    0     0          0         0 33091307388 86658381    0    0    0     0       0          0 '
> Apr 11 22:15:02 '  eth1:30708569308 91220742    0    0    0     0          0         0 122989732601 125074712    0    0    0     0       0          0 '
> 
> On another server (same hardware except for 2ru case, more ram and more hds):
> 
> Apr  9 06:18:05 '  eth0:1556640056941 3598105481    0    0    0     0          0         0 2281147324747 3318270401    0    0    0     0       0          0 '
> Apr  9 06:18:05 '  eth1:912389249044 1190286687    0    0    0     0          0         0 642943095469 991257887    0    0    0     0       0          0 '
> Apr  9 06:19:04 '  eth0:14250798570591813804 2284720007938 18638    0    0 18638          0  27375938 1556640980159 3345714490    0    0    0     0       0          0 '

0xc5c5_01cb_c5c5_00ac and 0x213_f3ec_ab02

The first one looks like trashed memory: it got overwritten by kernel
addresses.  Except they're x86-32 kernel addresses, and you're running
x86_64 64-bit kernel.  hm.

I don't see any pattern here.

> Apr  9 06:19:04 '  eth1:912389281939 1190287072    0    0    0     0          0         0 642943219035 991258183    0    0    0     0       0          0 '
> Apr  9 06:20:05 '  eth0:1556643514710 3598121584    0    0    0     0          0         0 2281154391794 3318284878    0    0    0     0       0          0 '
> Apr  9 06:20:05 '  eth1:912389305767 1190287354    0    0    0     0          0         0 642943273879 991258351    0    0    0     0       0          0 '
> 
> > > This happens on an AMD64, dual core smp box with Broadcom NetXtreme II
> > > nics.
> > 
> > What driver drivers that?  b44.c?
> 
> To clarify it's an Intel Dual Core Xeon (I just wound up as thinking of
> them all as amd64s). Network card driver in use is the one defined by
> CONFIG_BNX2. Kernel's monolithic.
> 
> > We do perform racy 64-bit updates of some of the stats counters.  But
> > that'll only affect 32-bit kernels and I'm assuming you're running a 64-bit
> > kernel on that AMD64 box (are you?)
> 
> Yes. With 32bit compat for executables built in.

OK.  I was earlier assuming that you were seeing transient funny numbers. 
But in fact I think you're saying that the numbers go bad, and then stay
bad.

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