[ovs-dev] [PATCH net-next 4/4] net: Add Open vSwitch kernel components.

[Stephen Hemminger]

> On Fri, Nov 18, 2011 at 3:23 PM, Stephen Hemminger
> <shemminger at vyatta.com> wrote:
> > On Fri, 18 Nov 2011 15:12:18 -0800
> > Jesse Gross <jesse at nicira.com> wrote:
> >
> >> +             write_seqcount_begin(&stats->seqlock);
> >> +             stats->tx_packets++;
> >> +             stats->tx_bytes += sent;
> >> +             write_seqcount_end(&stats->seqlock);
> >
> > There is a u64_stats_sync set of macros for this. It has the
> > advantage of becoming a NOP on 64 bit platforms.
> 
> The reason why I did it this way is it ties the packet and byte count
> together.

Ok, but why bother?
No other software counters bother to group bytes/packets. Even
hardware counters get read separately.