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Date: Wed, 05 Mar 2008 16:00:23 -0600 From: "Chris Friesen" <cfriesen@...tel.com> To: "Kok, Auke" <auke-jan.h.kok@...el.com> CC: Todd Tomaino <ttomaino@...ulet.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: E1000: e1000_update_stats() Kok, Auke wrote: > the update_stats function is only called every two seconds, and scheduled once. I > think that the chance that two of these functions run in contention in the way you > point out are practically zero, and if they do then we have much bigger problems > than just counters being wrong... I recently did an investigation that ended up sampling a subset of those stats every millisecond (to get an accurate picture of how many packets were being arriving vs being dropped due to rx_fifo errors over short intervals). Ultimately it turned out that we had very bursty traffic. So it's not entirely unheard-of to sample at much higher rates. At the very least, if we're going to remove the atomicity of reading registers and updating stats, how about adding a comment to this effect in the code? Chris -- 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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