On Wed, 2012-06-06 at 21:43 +0300, Michael S. Tsirkin wrote: > 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. As soon as you read a value, it might already have changed. Maybe you want to stop_machine() to make sure all the metrics you want are 'exact' ;) > 2. 32 bit systems have some overhead because of the seqlock. > virtio could instead simply keep tx counters in the queue structure, and > get the tx lock when they are read. > But then you need atomic64 stuff, have you an idea of the cost of such primitives on 32bit ? 3. use 32bit counters on 32bit arches, as many drivers still do ? _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
