On 16/05/2016 10:14, Felix Fietkau wrote: > On 2016-05-16 10:48, Hannu Nyman wrote: >> I already said to Felix yesterday that I felt that with kernel 4.4 my ar71xx >> WNDR3800 seemed somehow more sluggish. Now I tested the matter with "flent". >> >> And sadly, with kernel 4.4 my router's performance decreases significantly. >> With kernel 4.1 the router achieves about 20% higher download throughput >> than >> with the 4.4 build :-( >> >> I used "flent" to measure wired connection throughput with >> - two LEDE builds: r241 with kernel 4.1 and r253 with kernel 4.4 >> - two separate speed limits for SQM simple fq_codel QoS: 85000/10000 kb/s >> that should leave some CPU power free in the router, and 110000/15000 that >> should fully utilise the router's CPU. >> - otherwise identical settings, all measurements made inside 30 minutes so >> no >> changes in traffic conditions >> >> The achieved speeds were: >> >> r241 kernel 4.1 - 85/10: 79 Mb/s down, 8.1 Mb/s up >> r253 kernel 4.4 - 85/10: 67 Mb/s down, 8.5 Mb/s up >> >> r241 kernel 4.1 - 110/15: 85 down, 10.5 up >> r253 kernel 4.4 - 110/15: 70 down, 10.8 up >> >> (ping latency stays at 16-17 ms with all four tries) >> >> With both SQM speed limits, the kernel 4.1 build performs significantly >> better. >> >> This performance decrease might be due to the kernel version bump to 4.4 or >> the qdisc/codel changes made to the 4.4 patches a few days earlier. >> >> This chart sums it up: >> https://www.dropbox.com/sh/89pntkzjxydnn4c/AAC4x9cScJERL9Wfxm4k43kma?dl=0&preview=Kernel41_44_comparison.png >> >> Full flent data (summary pics & rrul data files) for all four tries is >> available in: >> https://www.dropbox.com/sh/89pntkzjxydnn4c/AAC4x9cScJERL9Wfxm4k43kma?dl=0 > I've also noticed a throughput decrease on other platforms, I don't have > any hard data on that though. I've tried tracking down the source of > this regression, but haven't gotten anywhere with that yet. > > Once we're done with more urgent stuff, I plan to do some more work on > optimizing the network stack. I've already expressed my concern that the fq_codel batch drop backport, backports more than it need to http://lists.infradead.org/pipermail/lede-dev/2016-May/000349.html
Now whether the backport extras are a significant resource drain or not isn't something I know or are in a position to test. Another opinion/idea/guess for the pot :-) Kevin _______________________________________________ Lede-dev mailing list Lede-dev@lists.infradead.org http://lists.infradead.org/mailman/listinfo/lede-dev
