faster eth0 = slower eth1


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Thread: faster eth0 = slower eth1

  1. #1
    Join Date
    Nov 2002
    Posts
    12

    faster eth0 = slower eth1

    I've searched forums, sites, I'm very frustrated because as far as I'm concerned this is rediculous..

    So I ftp my box to checkout lan speed - I get 4.5mb/sec (eth1). Not bad considering it's an old P1 and the scsi raid seems to max out at 4-6MB/per disk.

    So I go to download a torrent - downloads at 60kb/sec... (eth0)

    I happen to need to ftp something to the box from my winxp client - transfer is at 400-800kb/sec down from 4.5MB..

    File is huge, i have time to pause the torrent, as soon as I pause it and there is no activity on eth0, eth1 jumps back up to 4.5MB/sec... I resume the torrent, back down to x KB/sec... there is a function f(x) where the eth1 speed seems to depend on x (x being the eth0 speed).. because once the torrent slows down to say 20-30kb/sec, eth1 jumps back up to 1-1.5MB/sec.

    What's the deal here? How can traffic from net to box on eth0 affect traffic from winxp client to box on eth1?

    I just don't get it..

    Any suggestions before I try another net card and another firewall?
    (I'm new to linux, so maybe there is a quickfix I don't know about).

    Box:
    Linux Redhat 9.0, Shorewall 1.4.8
    P1 233MMX, 256MB SDRAM
    eth0: 3com cyclone (3c59x)
    eth1: D-Link 530+ (tulip)
    4GB IDE root, 5 Disk SCSI SCA Array, md0: 9gb, md1: 4gb, sde1: 18GB - all on a 220W power supply!!! (+ floppy + 4/8GB DAT2 + 12X SCSI CDROM)
    - array on AIC7xxx, tape drive / cdrom on AHA1542
    Last edited by Vortex; 12-23-2003 at 02:14 AM.

  2. #2
    Join Date
    Dec 1999
    Location
    Winnipeg,Manitoba,Canada
    Posts
    1,578
    When you do an ifconfig... are both of your nics on the same interrupt??
    search first, ask second.
    gui tool? what is a gui tool?
    I want my 5 stars back.....

  3. #3
    Join Date
    Nov 2002
    Posts
    12
    Yeah I did some investigating...

    First thing I thought of (and changed) was the IRQs, they were the same, however, the sharing (I suppose it's called) was working correctly because it didn't seem to help...

    Other clues which I discovered:

    - it wasn't the firewall, I tested ftp with FW off,
    - it happened both ways (ftp DL and UL), so it wasn't write particular
    - at first I thought it was the torrent client written in python, but then opera transfers made ftp slow too
    - it didn't happen when the traffic was going to a LAN client (if a client was downloading fast, ftp UL to box was still fast)

    and so that last one gave it away...
    i feel like such an idiot

    I'm pretty sure the CPU and PCI bus are getting maxed out.

    The CPU because there is a significant ftp throughput drop when loading X and jumps back up when it's done, and the PCI bus because an ftp UL to an IDE disk slowed down a file being copied from one SCSI disk to another via a UW SCSI controller.. although that could have been the CPUs fault also.. either way, no matter what I do, it seems everything is maxed out at about 6MB/s and shared between any kind of disk writing.

    proftpd uses 45% cpu when trying to write as fast as possible
    lynx about 35% when downloading at 150-200kb/sec
    when downloading in opera, mouse slows down
    when moving mouse in circles in X, ftp speed decreases

    Guess a P1 ain't what it used to be
    and it sure as hell isn't doing what I need it to do...

    sigh, time to grab an AMD + board + ram + psup...

    I doubt this 220W will be able to handle that new beast...

    Anyways, thanks for the effort guys, I saw the number of glances for this thread

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