From: "Chris Friesen" <cfriesen@nortel.com>
To: "Kok, Auke" <auke-jan.h.kok@intel.com>
Cc: Todd Tomaino <ttomaino@rivulet.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: E1000: e1000_update_stats()
Date: Wed, 05 Mar 2008 16:00:23 -0600 [thread overview]
Message-ID: <47CF17F7.4030405@nortel.com> (raw)
In-Reply-To: <47CF136A.8070202@intel.com>
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
next prev parent reply other threads:[~2008-03-05 22:00 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-05 20:45 E1000: e1000_update_stats() Todd Tomaino
2008-03-05 21:22 ` Chris Friesen
2008-03-05 21:40 ` Kok, Auke
2008-03-05 22:00 ` Chris Friesen [this message]
2008-03-05 21:34 ` Kok, Auke
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