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Opened 2 years ago

Last modified 2 years ago

#20860 new defect

Routing of higher bandwidth results in ~100% CPU usage

Reported by: anonymous Owned by: developers
Priority: normal Milestone:
Component: packages Version: Trunk
Keywords: Cc:

Description

I have a 100/40mbit WAN connection, and downloading at near max of 100mbit results in 100% CPU usage on a Netgear WNDR3800 and leads to drops of bandwidth. Is this normal or a bug? I would assumed this router should be able to do this kind of bandwidth routing.

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Change History (9)

comment:1 Changed 2 years ago by hnyman

Sounds normal. With a 100 Mbit/s internet connection, you are hitting the performance limit of the router.

WNDR3700 & WNDR3800 are able to route some 80-100 Mbit/s traffic (down+up together) depending a bit on the possible QoS system.

My own WNDR3800 results last year with a 100/15 Mbit/s wan connection:
I tested using netperf-wrapper with no shaping, with sqm-scripts and with qos-scripts:
Nothing: 50 ms latency, about 98/11 Mb speed (ellipsis center).
SQM 100/11 Mb: 18 ms and 82/9 Mb speed.
QoS 100/11 Mb: 18 ms and 95/9 Mb speed

comment:2 Changed 2 years ago by daniel.petre@…

netgear wndr3700 and wndr3800, d-link dir-825 should be able to route around 200 Mbit/s WAN - LAN.

comment:3 Changed 2 years ago by anonymous

I don't use any QoS scripts with my image r47183. And no, definitely no, I cant see how 200mbit should work, the CPU caps already, like I said and this ticket is about, when I route a traffic of about 90-100mbit through WAN. Is this maybe because OpenWRT uses software NAT? I can see 200mbit possible maybe on the default image by Netgear, but not with OpenWRT.

Or someone has other results on this?

comment:4 follow-up: Changed 2 years ago by anonymous

WNR4900 support 200mbit and more with openwrt

comment:5 in reply to: ↑ 4 Changed 2 years ago by guenti

Replying to anonymous:

WNR4900 support 200mbit and more with openwrt

But not when built with musl because FPU was disabled.

comment:6 follow-up: Changed 2 years ago by anonymous

What does that mean? I have compiled my image with musl, is it bugged? My router is still the WNDR3800 btw so please keep it to that... not the WNR4900.

comment:7 in reply to: ↑ 6 Changed 2 years ago by anonymous

Replying to anonymous:

What does that mean? I have compiled my image with musl, is it bugged? My router is still the WNDR3800 btw so please keep it to that... not the WNR4900.

oh sorry, i misread..

comment:8 Changed 2 years ago by nbd

are you using QoS?

comment:9 Changed 2 years ago by anonymous

Thread starter here, no, like I said, I don't have QoS scripts build into my image. Is there a way to debug, what part of the system is using that much CPU? When using htop I just see overall CPU going to 100%, no process. So I guess it's some kernel module or something. I am using marked/flagged routing though a lot, but not in this case, because on my test PC client it's a global rule: "ip rule add prio 32760 from 10.0.0.11 table isp1" and table isp1 has just one entry for the WAN going, "ip route add default via 10.0.1.203 dev eth1 table isp1" to a 2nd router, so it's double NAT.

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