Re: Scalability of interface creation and deletion

On Sat, May 7, 2011 at 6:54 PM, Eric Dumazet [off-list ref] wrote:

synchronize_rcu() calls are not consuming cpu, they just _wait_
rcu grace period.

I suggest you read Documentation/RCU files if you really want to :)

If you want to check how expensive it is, its quite easy:
add a trace in synchronize_net()

<snip>

I proposed adding a "wait" software counter to perf [1] a while ago,
which would allow people identify sync_rcu hotspots:

http://marc.info/?l=linux-kernel&m=129188584110162

I don't know how much visibility it got, so given this context, I
thought of bringing it up again :)