[Cake] Peeling question

Sebastian Moeller moeller0 at gmx.de
Wed Aug 26 10:52:14 EDT 2015

Hi Jonathan, hi Dave,

I have just been discussing GRO/LRO/TSO/GSO type meta packets (for lack of a better name) and their influence on temporal traffic shaping granularity (and fine timescale fairness). I know that cake solves this problem the most elegant way by peeling/decomposing the meta packets into nice pMTU sized chunks, but until cake hits openwrt or mainline we need to get away with bigger hammers, namely disabling meta-packets entirely. I believe that they need to be disabled on all interfaces to be effective as say a meta-packets assembled on say a WLAN-interface with GRO enabled will e passed onto WAN even if the WAN-interface has GSO disabled, is that correct? 
	So the 1. question boils down to on which interfaces the offloads need to be disabled, on all interfaces or only on “real” interfaces? Or more specifically with cerowrt nomenclature: will ge00 be sufficient or do I also disable it in pppoe-ge00 and ifb4pppoe-ge00? By default GSO and GRO are enabled on those interfaces?
	My second question is how do you guys actually test this? How can I create a situation with a very high likelihood of meta-packets appearing? (If I know this I can go figure question 1 myself…)

On a related note it would be sweet if cake could report the maximal sizes of packets it gets fed in and the maximum sizes it ejects; so for non-peeled meta-packets I expect to see say in: 64K out: 64K and for peeled rather in: 64K out: 1514 or so.

Best Regards

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