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Message-ID: <1179796504.1661.152.camel@dell> Date: Mon, 21 May 2007 18:15:04 -0700 From: "Michael Chan" <mchan@...adcom.com> To: "CaT" <cat@....com.au>, jd@...junkt.com cc: "Andrew Morton" <akpm@...ux-foundation.org>, linux-kernel@...r.kernel.org, "netdev" <netdev@...r.kernel.org> Subject: Re: intermittant petabyte usage reported with broadcom nic 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. We were able to reproduce the problem and confirmed that it was a DMA problem of the statistics block. About once an hour on average, wrong counter values will be DMA'ed to host memory. Luckily, the DMA write stays within the intended address range so it will not corrupt other parts of memory. Other types of DMA including traffic and buffer descriptors are not affected. If you happen to be reading /proc/net/dev within a second after the DMA corruption, you'll see bogus counters. One second later and until the next bad DMA, the counters will be normal again. We are considering ways to workaround the problem. Thanks. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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