Greetings Ilpo, On 04/12/2007, Ilpo Järvinen <[EMAIL PROTECTED]> wrote: > On Mon, 3 Dec 2007, Lachlan Andrew wrote: > > > > When SACK is active, the per-packet processing becomes more involved, > > tracking the list of lost/SACKed packets. This causes a CPU spike > > just after a loss, which increases the RTTs, at least in my > > experience. > > I suspect that as long as old code was able to use hint, it wasn't doing > that bad. But it was seriously lacking ability to take advantage of sack > processing hint when e.g., a new hole appeared, or cumulative ACK arrived. > > ...Code available in net-2.6.25 might cure those.
We had been using one of your earlier patches, and still had the problem. I think you've cured the problem with SACK itself, but there still seems to be something taking a lot of CPU while recovering from the loss. It is possible that it was to do with web100 which we have also been running, but I cut out most of the statistics from that and still had problems. Cheers, Lachlan -- Lachlan Andrew Dept of Computer Science, Caltech 1200 E California Blvd, Mail Code 256-80, Pasadena CA 91125, USA Ph: +1 (626) 395-8820 Fax: +1 (626) 568-3603 http://netlab.caltech.edu/~lachlan -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
