Bufferbloat Is Still Being Fought In Linux Kernel, Another Big Improvement Queued

[SystemCrasher]

As far as I understand this patch, it isn't about further bufferbloat fights, just about speeding it up in some nasty corner cases.

[cj.wijtmans]

So this is why i have hitter and latency issues with ns2. I already started reducing latencies in interrupts and task switching by tweaking my kernel and some settings. And i must say it already helped a great deal. I just have to wait for the nvidia 10xx benchmarks to upgrade get a 144hz monitor and get more efficient netcode and it would help a great deal as well. Which BTW i found a bug with the kernel. TSC clocks at 3400mhz reported by my firmware but my cpu is oced at 4000mhz so the TSC is not really synched with my cpu hz. I dont know if this is an issue.

[speculatrix]

The default transmit queue in Linux is 1000, which is quite a long time with 1000 byte packets over gigabit. It breaks the TCP congestion feedback strategy. Any fresh TCP connections are then stuck at the back of the queue.
I found that reducing the queues to under 100 on my Linux firewall made things more responsive when doing long running downloads, e.g. streaming video.

[dtaht]

SystemCrasher is correct, that patch is about cleaning up a nasty corner case. Lost in the keruffle tho, was the context of why that patch came about - we are just starting to move fq_codel into the mac80211 layer of the wifi stack with wonderful results - factor 50x reduction in latency, no loss in throughput at 6mbits, 5x at 100mbits...

http://blog.cerowrt.org/post/fq_codel_on_ath10k/

was the breakthrough. I figured after a bit more polishing and getting it closer to upstreaming, we'd put out a press release, but I ended up having to do quite a bit more analysis than I'd wanted.

http://blog.cerowrt.org/post/

but summarizing the results here:
http://blog.cerowrt.org/post/anomolies_thus_far/

The end is nigh for lousy, flaky, over-latent wifi performance.

...

I do keep hoping one day more folk would utilize flent to analyze their network performance and latency.

--
Dave Täht
Let's go make home routers and wifi faster! With better software!
http://blog.cerowrt.org