Anton Vorontsov wrote:
On Tue, Jul 07, 2009 at 11:47:38AM -0700, Rick Jones wrote:
Admittedly, all the world is not TCP, but a big chunk is, so are you
likely to have reference counts go to zero on the tx queue for
anything other than small standalone TCP ACK segments?
That's a generic question wrt skb recycling, right? Whether we can
always recycle transmitted skbs. No, sometimes (or mostly) we can't.
Initially, I was quite puzzled by this support... looking at how
gianfar driver works (it has the same support as of 0fd56bb5be6455d0),
I noticed that skb_recycle_check() always returns 0, and so we
don't recycle the skbs.
Though, things change when the kernel starts packets forwarding,
*then* skb recycling path actually triggers.
Lennert (skb recycling author) hints us that the gain is indeed
in forwarding/routing workload:
http://kerneltrap.org/mailarchive/linux-netdev/2008/9/28/3433514
>
Hope I understood everything correctly. :-)
Given the text reads:
This gives a nice increase in the maximum loss-free packet forwarding
rate in routing workloads.
Your understanding is probably correct. Might have been "nice" :) to get a
definition of a "nice increase" though :)
rick jones
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