Le mardi 15 mars 2011 à 15:36 -0700, Rick Jones a écrit : > Back and forth synchronization between driver and device is > doubleplusungood. Being able to remove a packet on the tx queue already > made known to the NIC sounds like it could become a rathole. If you are > lucky, you *might* have a "valid/invalid" bit in a packet descriptor > that the driver could hope to set before the NIC had pulled-in a copy > across the I/O bus.
There are two different use cases : 1) Wired devices, where we want to push more 10+ Gbps, so we can assume a posted skb is transmitted immediately. Even a basic qdisc can be a performance bottleneck. Set TX ring size to 256 or 1024+ buffers to avoid taking too many interrupts. 2) wireless, were typical bandwidth is small enough we can afford a qdisc with a trafic shaper, good flow classification, whatever limit on "maximum waiting time in qdisc queue or drop it" and a very small queue on hardware ? In both cases, we dont need to "cancel" a packet post to NIC hardware, or we need special hardware support (some NICS already provide hardware TX completion times) _______________________________________________ Bloat mailing list [email protected] https://lists.bufferbloat.net/listinfo/bloat
