Severe LAN/WLAN slowdowns

Discussion in 'Tomato Firmware' started by atrus, Jul 3, 2008.

  1. atrus

    atrus Addicted to LI Member

    I'm using a WRT54GL running Tomato 1.19.

    I have a mythtv box on a LAN port, and a laptop that connects via wireless. After watching television for a while this way, my speeds drop dramatically.

    This effect persists after mythtv has exited. After that point, an ssh copy will get ~100kbytes/second, whereas i normally see ~1.5mbytes/second.

    The only solution I've found so far is to reboot the WRT54GL, at which point I get back to full speed again.

    It's a stock install, with no real customization, and only a few days old.

    Any suggestions welcome. Thanks.
  2. HennieM

    HennieM Network Guru Member

    I can't help you, but I would try to localize the problem:-

    Do a "free" and see how much mem you have. If mem is depleted, try find out which process is eating it.
    Do "top" and see which processes are running, using CPU, and mem.
    Do "cat /proc/net/ip_conntrack" and see how many connections you have. If these seem excessive, try shrinking the TCP and/or UDP timeouts.
    Try turning WMM/WME off if on, or on if off.
  3. atrus

    atrus Addicted to LI Member

    # free
                  total         used         free       shared      buffers
      Mem:        14528        10232         4296            0         1136
     Swap:            0            0            0
    Total:        14528        10232         4296
    I'm guessing that doesn't qualify as "depleted" yet?
    # cat /proc/net/ip_conntrack | wc -l
    Is that excessive? If so, what should I be shrinking, and how much? :)
    These are QoS options right? I don't have QoS enabled...
  4. atrus

    atrus Addicted to LI Member

    I do seem to get ALOT of ARP traffic from upstream on my cable modem. Could that be involved at all?

    EDIT: Except that the problem is completely invisible for days until I go to run mythtv for a while, so that wouldn't really make sense.
  5. HennieM

    HennieM Network Guru Member

    Mem is good - when Free and Buffers together are close to zero - bad.
    Conntrack is good - 63 connections is certainly not excessive.
    WMM/WME is a built-in wireless protocol extension, and is independant from QoS. In Tomato: Advanced > Wireless > WMM.

    What does "top" show?

    Question: Did you take those readings while the router was slow? If not, do so when the router is slow, as only then will you see what's causing the problem. If so, then I can't see why the router is slow - answer may be in "top", i.e. CPU utilization.

    I can't see what upstream ARP traffic would do, except if it's so excessive that it eats CPU.
  6. atrus

    atrus Addicted to LI Member

    Enabling/disabling WMM makes no difference.
    Mem: 11328K used, 3200K free, 0K shrd, 1224K buff, 4240K cached
    Load average: 0.16 0.04 0.01  (Status: S=sleeping R=running, W=waiting)
     1331 root     R        372  1328  1.3  2.5 top
     1327 root     S        636    89  1.0  4.3 dropbear
        1 root     S        540     0  0.0  3.6 init
     1325 nobody   S        508     1  0.0  3.4 dnsmasq
      836 root     S        480     1  0.0  3.2 nas
      938 root     S        472     1  0.0  3.2 upnp
     1328 root     S        440  1327  0.0  3.0 sh
       89 root     S        404     1  0.0  2.7 dropbear
      846 root     S        368     1  0.0  2.5 crond
     1037 root     S        348     1  0.0  2.3 udhcpc
      850 root     S        336     1  0.0  2.2 rstats
      832 root     S        332     1  0.0  2.2 syslogd
      835 root     S        312     1  0.0  2.1 klogd
      843 root     S        308     1  0.0  2.1 httpd
       39 root     S        264     1  0.0  1.8 buttons
       84 root     S        264     1  0.0  1.8 telnetd
        3 root     SWN        0     1  0.0  0.0 ksoftirqd_CPU0
        7 root     SW         0     1  0.0  0.0 mtdblockd
        2 root     SW         0     1  0.0  0.0 keventd
        6 root     SW         0     1  0.0  0.0 kupdated
        4 root     SW         0     1  0.0  0.0 kswapd
        5 root     SW         0     1  0.0  0.0 bdflush
    Yeah, these results are all while the router is operating below expected speed.
  7. atrus

    atrus Addicted to LI Member

    I've also discovered significant (read: 30-40%) packet loss on attempts to ping the router wirelessly and when transfers are slow.
  8. HennieM

    HennieM Network Guru Member

    Can't see anything, but it sounds like some buffer somewhere is full.
    Perhaps make sure Frameburst is on, UPnP off, and you have it on G-only. Dunno if that would help, but it's something to try.
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