Mandi! Dave Taht In chel di` si favelave... > >> The two treatments of quantum are very different. > > Very clear, thanks. > Took me a long while to figure it out! ...and seems to me that we need a wiki to write down all that stuff... > We have improved this in later versions of fq_codel (cake), so it > figures it out for you. i'm on a debian wheezy, so kernel 3.2.0-4-686-pae and tc as of iproute2 package version 3.12.0-2, from backports. So i think i need to wait some more time to eat the cake. ;-) So, to try to sum your ''rule of thumb'': QUANTUM: + for ASYMMETRIC lines running around at 20Mbit/s (downlink) or less, it is better to set 'quantum' to 300 (bytes), that is roughly 4 ipv4 ACK to leave fq_codel do ''automatic ACK priorization''. + for any other case, leave at the default. Any ''manual ACK priorization'' is anyway considered ''deprecated'' by fq_codel, that do it internally and more eefficiently. A question: 'quantum 300' have to be set on egress, or on ifb/ingress side? Or both? TARGET and INTERVAL: + considering indipendently egress and ingress (so, companion ifb interface), if rates is > 2.5Mbit/s, leave the default value. + if rate is lower, it is needed to account for one MTU, in milliseconds, rounding a bit higher. if MTU=1500 and BANDW=640Kbit/s, the MTU in milliseconds is: 1500*8/640000 = 19ms so we can round it to 20ms; A question: interval it is safe to keep as 150ms? Or it is better to change also that accordingly? or it is unrelated, so it is better to set with other criteria? + at really low rates, roughly under 1Mbit/s, probably it is better to keep using SFQ instead of fw_codel, that is oriented with modern, high rates. Say me if i've understood well. Thanks. -- dott. Marco Gaiarin GNUPG Key ID: 240A3D66 Associazione ``La Nostra Famiglia'' http://www.sv.lnf.it/ Polo FVG - Via della Bontà, 7 - 33078 - San Vito al Tagliamento (PN) marco.gaiarin(at)lanostrafamiglia.it t +39-0434-842711 f +39-0434-842797 Dona il 5 PER MILLE a LA NOSTRA FAMIGLIA! http://www.lanostrafamiglia.it/25/index.php/component/k2/item/123 (cf 00307430132, categoria ONLUS oppure RICERCA SANITARIA) -- To unsubscribe from this list: send the line "unsubscribe lartc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
