[ovs-dev] [PATCH] datapath: Use u64_stats_sync for datapath and vport stats.

[Ben Pfaff]

On Sat, Nov 19, 2011 at 10:20:24AM -0800, Jesse Gross wrote:
> We currently use a seqcount to prevent reading partial 64-bit stats
> on 32-bit CPUs.  u64_stats_sync uses the same logic but elides it on
> 64-bit and uniprocessor machines.  This improves performance (primarily
> on non-x86 architectures) at the cost of not guaranteeing that packet
> and byte counts were necessarily read together.
> 
> Suggested-by: Stephen Hemminger <shemminger at vyatta.com>
> Signed-off-by: Jesse Gross <jesse at nicira.com>

Acked-by: Ben Pfaff <blp at nicira.com>

(These acks are going to look silly going upstream, maybe we should
switch to "Looks good." for the datapath :-)

I don't see anything that documents how one initializes a
u64_stats_sync.  I guess all-zero-bits initialization is sufficient,
and it looks like percpu data is initially zeroed.