On Wed, Jun 06, 2012 at 10:06:11PM +0200, Eric Dumazet wrote:

On Wed, 2012-06-06 at 21:43 +0300, Michael S. Tsirkin wrote:

quoted

1. We are trying to look at counters for purposes of tuning the device.
E.g. if ethtool reports packets and bytes, we'd like to calculate
average packet size by bytes/packets.

If both counters are read atomically the metric becomes more exact.
Not a must but nice to have.

metrics are exact right now.

Yes, but they are not synchronised between themselves.
E.g. you can in theory have a report where #of packets > #of bytes.

I know there's no guarantee they are synchronised
on an arbitrary device but if they are, without
slowing fast path, it's nice.