On Sat, 30 May 2009 12:41:00 am Eric Dumazet wrote: > Rusty Russell a écrit : > > DaveM points out that there are advantages to doing it generally (it's > > more likely to be on same CPU than after xmit), and I couldn't find > > any new starvation issues in simple benchmarking here. > > If really no starvations are possible at all, I really wonder why some > guys added memory accounting to UDP flows. Maybe they dont run "simple > benchmarks" but real apps ? :) Well, without any accounting at all you could use quite a lot of memory as there are many places packets can be queued. > For TCP, I agree your patch is a huge benefit, since its paced by remote > ACKS and window control I doubt that. There'll be some cache friendliness, but I'm not sure it'll be measurable, let alone "huge". It's the win to drivers which don't have a timely and batching tx free mechanism which I aim for. > , but an UDP sender will likely be able to saturate > a link. I couldn't see any difference in saturation here (with default scheduler and an 100MBit e1000e). Two reasons come to mind: firstly, only the hardware queue is unregulated: the tx queue is still accounted. And when you add scheduling to the mix, I can't in practice cause starvation of other senders. Hope that clarifies, Rusty. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
