OpenWrt Forum Archive

Topic: wan speed drops by 20 mbits with enabled wifi on wr842n v3

The content of this topic has been archived on 29 Apr 2018. There are no obvious gaps in this topic, but there may still be some posts missing at the end.

Post #1
nozombian
12 Feb 2018, 21:12

Hello, I have latest lede snapshot on wr842n v3. With disabled wifi I get 85mbit throughput (wan to lan), when I enable wifi, wan to lan speed drops to only 65 mbit. There's no station connected of course and wifi and key are fresh and random, none knows them.

TP lInk wr842n V3 is quite good hw, atheros 650MHz cpu, 64MB RAM, 16MB flash.

What can that be?

On TP link wr841n V13 with mediatek 580MHz CPU, 64MB RAM and 8MB flash I don't have this problem (wifi is still unusable, but at least it does not slow the router down).

Post #2
moeller0
13 Feb 2018, 10:15

What does "top -d 1" show for both conditions (so during the throughput test ith and without wifi enabled)? Especially is the idle value in one condition close to zero?

Post #3
nozombian
13 Feb 2018, 21:06

CPU is surely not the bottleneck, with wifi disabled only measurable higher usage is on net interface, because router has 100mbit switch only and without wifi it has throughbut closer to 100mbit.

This is with wifi enabled, during 65mbit throughput on speedtest, with disabled wifi it's quite the same (except hostapd):

Mem: 20436K used, 40032K free, 88K shrd, 1964K buff, 5504K cached
CPU:   0% usr   0% sys   0% nic  64% idle   0% io   0% irq  33% sirq
Load average: 0.12 0.03 0.01 1/38 2172
  PID  PPID USER     STAT   VSZ %VSZ %CPU COMMAND
  102     2 root     SW       0   0%   7% [kworker/0:1]
 2172  2099 root     R     1208   2%   4% top -d 1
 1121     1 root     S     1692   3%   3% /usr/sbin/hostapd -s -P /var/run/wifi-phy0.pid -B /var/run/hostapd-phy0.conf
 2098   751 root     S     1132   2%   3% /usr/sbin/dropbear -F -P /var/run/dropbear.1.pid -p 8022 -K 300 -T 3
    3     2 root     SW       0   0%   3% [ksoftirqd/0]
    8     2 root     SW       0   0%   1% [kworker/u2:1]
  692     1 root     S     1716   3%   0% /sbin/netifd
    1     0 root     S     1536   3%   0% /sbin/procd
 1507     1 dnsmasq  S     1316   2%   0% /usr/sbin/dnsmasq -C /var/etc/dnsmasq.conf.cfg01411c -k -x /var/run/dnsmasq/dnsmasq.cfg01411c.pid
  610     1 root     S     1224   2%   0% /sbin/logd -S 64
  911     1 root     S<    1208   2%   0% /usr/sbin/ntpd -n -N -l -S /usr/sbin/ntpd-hotplug -p 0.lede.pool.ntp.org -p 1.lede.pool.ntp.org -p 2.lede.pool.ntp.org -p 3.lede.pool.n
 2165     1 root     S     1208   2%   0% /usr/sbin/crond -f -c /etc/crontabs -l 5
 2099  2098 root     S     1204   2%   0% -ash
 1240   692 root     S     1204   2%   0% udhcpc -p /var/run/udhcpc-eth1.pid -s /lib/netifd/dhcp.script -f -t 0 -i eth1 -x hostname:skn842 -C -O 121
  420     1 root     S     1184   2%   0% /sbin/ubusd
  751     1 root     S     1064   2%   0% /usr/sbin/dropbear -F -P /var/run/dropbear.1.pid -p 8022 -K 300 -T 3
  421     1 root     S      900   1%   0% /sbin/askfirst /usr/libexec/login.sh
 2135     2 root     SW       0   0%   0% [kworker/u2:0]
  206     2 root     SW<      0   0%   0% [bioset]
  196     2 root     SW<      0   0%   0% [bioset]
  300     2 root     SW<      0   0%   0% [kworker/0:1H]
  343     2 root     SW       0   0%   0% [kworker/0:2]
  374     2 root     SWN      0   0%   0% [jffs2_gcd_mtd3]
  191     2 root     SW<      0   0%   0% [bioset]
  201     2 root     SW<      0   0%   0% [bioset]
  211     2 root     SW<      0   0%   0% [bioset]
  109     2 root     SW       0   0%   0% [kswapd0]
   77     2 root     SW<      0   0%   0% [kblockd]
   75     2 root     SW<      0   0%   0% [bioset]
  167     2 root     SW       0   0%   0% [spi0]
   71     2 root     SW       0   0%   0% [oom_reaper]
   72     2 root     SW<      0   0%   0% [writeback]
    5     2 root     SW<      0   0%   0% [kworker/0:0H]
    2     0 root     SW       0   0%   0% [kthreadd]
    7     2 root     SW<      0   0%   0% [lru-add-drain]
   74     2 root     SW<      0   0%   0% [crypto]
  186     2 root     SW<      0   0%   0% [bioset]
  475     2 root     SW<      0   0%   0% [cfg80211]

idle with wifi on:

Mem: 20544K used, 39924K free, 88K shrd, 1964K buff, 5504K cached
CPU:   2% usr   1% sys   0% nic  94% idle   0% io   0% irq   0% sirq
Load average: 0.05 0.01 0.00 1/38 2173
  PID  PPID USER     STAT   VSZ %VSZ %CPU COMMAND
  102     2 root     SW       0   0%   3% [kworker/0:1]
 1121     1 root     S     1692   3%   1% /usr/sbin/hostapd -s -P /var/run/wifi-phy0.pid -B /var/run/hostapd-phy0.conf
 2173  2099 root     R     1208   2%   1% top -d 1
 2098   751 root     S     1132   2%   0% /usr/sbin/dropbear -F -P /var/run/dropbear.1.pid -p 8022 -K 300 -T 3
    3     2 root     SW       0   0%   0% [ksoftirqd/0]
  692     1 root     S     1716   3%   0% /sbin/netifd
    1     0 root     S     1536   3%   0% /sbin/procd
 1507     1 dnsmasq  S     1316   2%   0% /usr/sbin/dnsmasq -C /var/etc/dnsmasq.conf.cfg01411c -k -x /var/run/dnsmasq/dnsmasq.cfg01411c.pid
  610     1 root     S     1224   2%   0% /sbin/logd -S 64
  911     1 root     S<    1208   2%   0% /usr/sbin/ntpd -n -N -l -S /usr/sbin/ntpd-hotplug -p 0.lede.pool.ntp.org -p 1.lede.pool.ntp.org -p 2.lede.pool.ntp.org -p 3.lede.pool.n
 2165     1 root     S     1208   2%   0% /usr/sbin/crond -f -c /etc/crontabs -l 5
 2099  2098 root     S     1204   2%   0% -ash
 1240   692 root     S     1204   2%   0% udhcpc -p /var/run/udhcpc-eth1.pid -s /lib/netifd/dhcp.script -f -t 0 -i eth1 -x hostname:skn842 -C -O 121
  420     1 root     S     1184   2%   0% /sbin/ubusd
  751     1 root     S     1064   2%   0% /usr/sbin/dropbear -F -P /var/run/dropbear.1.pid -p 8022 -K 300 -T 3
  421     1 root     S      900   1%   0% /sbin/askfirst /usr/libexec/login.sh
    8     2 root     SW       0   0%   0% [kworker/u2:1]
 2135     2 root     SW       0   0%   0% [kworker/u2:0]
  206     2 root     SW<      0   0%   0% [bioset]
  196     2 root     SW<      0   0%   0% [bioset]
  300     2 root     SW<      0   0%   0% [kworker/0:1H]
  343     2 root     SW       0   0%   0% [kworker/0:2]
  374     2 root     SWN      0   0%   0% [jffs2_gcd_mtd3]
  191     2 root     SW<      0   0%   0% [bioset]
  201     2 root     SW<      0   0%   0% [bioset]
  211     2 root     SW<      0   0%   0% [bioset]
  109     2 root     SW       0   0%   0% [kswapd0]
   77     2 root     SW<      0   0%   0% [kblockd]
   75     2 root     SW<      0   0%   0% [bioset]
  167     2 root     SW       0   0%   0% [spi0]
   71     2 root     SW       0   0%   0% [oom_reaper]
   72     2 root     SW<      0   0%   0% [writeback]
    5     2 root     SW<      0   0%   0% [kworker/0:0H]
    2     0 root     SW       0   0%   0% [kthreadd]
    7     2 root     SW<      0   0%   0% [lru-add-drain]
   74     2 root     SW<      0   0%   0% [crypto]
  186     2 root     SW<      0   0%   0% [bioset]
  475     2 root     SW<      0   0%   0% [cfg80211]

(Last edited by nozombian on 13 Feb 2018, 21:07)

Post #4
moeller0
14 Feb 2018, 11:49

Ah, okay that is not it then, You could install iftop and look at the CPUs interfaces (but you probably thought about that already). Another idea, is the WAN port part of the switch or is it dedicated?

Post #5
nozombian
14 Feb 2018, 19:15

I don't know, but cheaper brother wr841n v11 also with atheros chipset does not suffer with this bug, at least I have never noticed that. But I cannot get my hands on atheros based wr841n, because they were replaced by mediatek since v13. Maybe some model specific bug?

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