On 09/01/2011 10:13 AM, John W. Linville wrote: > On Wed, Aug 31, 2011 at 01:50:48PM -0700, Luis R. Rodriguez wrote: >> On Wed, Aug 31, 2011 at 6:28 AM, Jim Gettys <jg@xxxxxxxxxxxxxxx> wrote: >> such as wireless, or even possibly modern broadband with >> PowerBoost, classic RED or similar algorithms that do not take the >> buffer drain rate cannot possibly hack it properly. >> Understood, just curious if anyone has tried a Minstrel approach. > FWIW, eBDP and the related algorithms from Tianji Li's paper are > philosophically similar to minstrel. They depend on measuring recent > conditions and modifying the current queue length accordingly. > > http://www.hamilton.ie/tianji_li/buffersizing.pdf > > The hack I added in debloat-testing is based on my understanding > of eBDP. It timestamps the SKBs when they are handed to the driver > for Tx and then checks the timestamp when the SKB is orphaned. It is > a bit crude and is an abuse of the skb_orphan API. Also while it > accounts for the 802.11e queues separately, it doesn't account for > 802.11n aggregation. Still, it seems to improve latency w/o hugely > impacting throughput in at least some environments -- YMMV! > Certainly eBDP *sort of* works for me; I see somewhat more variation (jitter) than I'd like, but at least latencies are at least somewhat controlled and I've not seen performance (throughput) problems. This is on an Intel chipset. Tanji Li's work and eBDP came to our attention after a conversation I had with Van at the beginning of this year; Van send me a pointer to it with the comments: "As I said on the phone I think there's an easier, more robust way to accomplish the same thing but they have running code and I don't." But we've not had time to do any systematic testing on eBDP yet and the implementation needs more work before it should go upstream. About the time we were thinking of starting that testing, it became clear that getting aggregation working better was pretty essential to validating any results. I'm looking forward to trying eBDP with the revised Ath9k driver as soon as they get put into a single pool. And if Kathleen and Van can get a "RED Light" they are happy with, that will be fun to try as well. - Jim -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
