Messages in this thread |  | | Date | Thu, 14 Sep 2000 06:53:37 -0400 (EDT) | From | jamal <> |
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On Thu, 14 Sep 2000, David S. Miller wrote:
> Date: Thu, 14 Sep 2000 04:44:53 -0400 > From: Jeff Garzik <jgarzik@mandrakesoft.com> > > Does anyone think that allocating skbs during system idle time > would be useful? > > I really don't like these sorts of things, because it makes an > assumption as to what memory is about to be used for. > > What if you were to preallocate skbs while idle, then the next thing > which happens is some userland program walks over a 2gb dataset and > no network activity happens at all. >
The FF code of the tulip does have skb recycling code. And i belive Jes' acenic code does or did at some point. Robert Olson and I were thinking of taking out that code out of the tulip for reasons such as you talk about (and the thought maybe that the per-CPU slab might have obsoleted that requirement). We did some tests with 2.4.0-test7 and were suprised to observe that at high rate of input packets, it still made as a big a difference as 7000 packets per second ;-> i.e we got 7Kpps more by using skb recycling.
Dave, would a scheme with an aging of the skbs in the recycle queue and an upper bound of the number of packets sitting on the queue be acceptable? Maybe ANK can make a comment as well. Robert and I plan to play with such a scheme for a long time under many different scenarios and come with numbers (throughput etc) instead of "here's a patch and intuitively it makes sense". This is really a 2.5 thing if acceptable.
cheers, jamal
PS:- OLS patch coming soon; a few more tests (as time permits);->
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