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low amount of free memory on tomato v1.23?

Discussion in 'Tomato Firmware' started by vibe666, Jan 17, 2009.

  1. vibe666

    vibe666 Network Guru Member

    I upgraded my WRT54GS v4 from Thibor15c to Tomato v1.23 about 12 days ago and I'm finding tomato a little sluggish after that amount of time and I'm wondering if there's anything I can do about it without rebooting the router.

    here's my total and free memory now: 14.19 MB / 1,156.00 KB (7.96%)

    is there anything I can do to free this up a bit and would this help performance or is it okay for it to be this low?

    I've tried dropping idle connections a few times and it seems to help a bit, but it always ends up feeling sluggish again fairly quickly.

    if I have to reboot it then I might clean NV ram again and restore my settings and see how it goes from there, but I was hoping not to have to reboot as this is hte longest my router has been up without needing a reboot since i bought it 3 years ago! :D

    also, is there a way to save the settings in the 'real time' bandwidth monitoring to green/blue solid? it keeps defaulting back to the original setting for some reason, even though the 24 hour one keeps it the way i want it.

    thanks for any help, loving the firmware by the way, very nice. :D
  2. Planiwa

    Planiwa LI Guru Member

    Hm. Is 1 MB of free RAM low? If we don't like the looks of "only" 1MB free RAM, we could turn on "count cache memory as free memory" in Admin > Debugging, and feel much better. :)

    Or, we could try to figure out what really makes the router sluggish.

    Perhaps the conntrack table size is too large? (supposedly larger is better -- I doubt it.) (Actually, many connections will lower free space, so, in that sense low free space is an indication of a router busy trying to set up (and tear down) futile connections.

    Perhaps too many idle entries? (Supposedly idle entries don't matter -- I doubt it.)

    Perhaps too many pointless connection attempts resulting from BT (or viruses)? Such connection surges can easily result in thousands of "connection" attempts in less than a minute. These surges are accompanied by hundreds of DNS requests, apparently originating from your router (!), so connlimit on the host won't catch them all.

    How busy is the router -- how many hosts, connections, packet, bytes?
    How much BT & other P2P?
    Have you checked #connections (Advanced > Conntrack/NF) when it feels sluggish?
    Checked the load average (Overview)

    IMHO, the greatest threat to router integrity are connection-surges, caused by out-of-control BT clients or games, etc, that knock on 1000's of doors, just in case someone answers.

    Your router could be happily moving data packets, or it could be scrambling in a furious frenzy trying to set up thousands of futile connections, only to clean up the failed half-baked mess a few seconds later.

    (A few minutes ago, one router told me that one host is using 1000 connections. Does anyone really need 1000 connections? There are 9 other hosts sharing that router.)

    If the source of sluggishness is too many overbearing connection (attempts), two measures might be reducing timeouts and imposing connlimits.

    (There is a problem on the Conntrack page in that the timeout for "unclassified" UDP is not listed. (Its value is the same as "assured", so at least it can be controlled.) But you will find that the categories listed do not (necessarily) add up. The difference, which will be great during a "futile connection surge", is "unclassified" UDP.)

    [The major cause of sluggishness in my routers is excessive monitoring to find and control the causes poor performance and instability. :-]

    I would be interested in other perspectives on router performance and stability issues, whether or not related to connection surges.
  3. vibe666

    vibe666 Network Guru Member

    conntrack is still set to the default values (I wouldn't know what to change them to anyway) and connections listed in there are averaging 700-1000 whenever I count them if i don't manually clear them, but with the default limit set to over 2000 i didn't think that *should* be a problem, but maybe it is?

    by far my main connection hog on the LAN is a Linux PC running bit torrent 24/7 but although network performance does seem sluggish it's not so bad that I can't do anything on the network, it's just sometimes i get some skipping when streaming divx's and that kind of thing.

    devices on the network are:

    2x WRT54GS in WDS mode (20mbps/1.5mbps cable broadband into router 1 acting as DHCP server etc.)
    Linux desktop PC (mostly used as a BT client and media server, but also webserver and some desktop tasks) - ethernet to router #2
    Windows XP Laptop (web browsing, email, RDP etc.) - ethernet to router #2 or wireless.
    Vista Netbook (web browsing, email etc.) - wireless
    Nintendo Wii - wireless
    Playstation 3 - ethernet to router #1
    Xbox (not 360) as media streaming device to TV. - ethernet to router #1
    Nokia n95 (web browsing etc. - wireless

    by and large, just about everything is working smoothly for the first time since I got my WRT's several years ago, I just wanted to know if I could improve things at all.

    aside from WDS and some port forwarding rules everything is set up as standard. is there anything I could do to improve things?

    thanks in advance. :)

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