[ovs-dev] [dpif-netdev 05/15] dpif-netdev: Use new "ovsthread_counter" to track dp statistics.

[Ben Pfaff]

On Mon, Dec 30, 2013 at 03:55:01PM -0800, Jarno Rajahalme wrote:
> 
> On Dec 30, 2013, at 3:32 PM, Ben Pfaff <blp at nicira.com> wrote:
> 
> > In the end, my goal here is to provide a useful abstraction and a
> > simple implementation that is likely to be correct.  Then, later, if
> > profiling shows that this is an actual bottleneck, we can optimize
> > it.  But I don't want to spend a bunch of time optimizing code that I
> > don't even know is important.
> 
> Would using a single atomic int be worse than using an array of
> locks? At least it would be simpler and obviously correct?

An atomic_uint would be easy, but the hit and miss and lost counts can
easily overflow UINT_MAX after a while.  atomic_ullong isn't portable,
unfortunately.

Maybe I will skip the whole controversy and just add a mutex around
these variables.  It might be slow, but it might not be the bottleneck
initially, and it would be obviously correct.

What do you guys think?