Re: limited network bandwidth with 3.2.x kernels

Eric Dumazet
2012-02-13T20:18:17Z

Le lundi 13 février 2012 à 22:04 +0200, alekcejk@googlemail.com a
écrit :
> Hi,
>
> I noticed that with 3.2.x kernels download speed from some internet resources
> became about half of speed that was with previous kernels (3.1 and older).
> I tested Fedora 15 kernels 2.6.41.10 = 3.1.10 and 2.6.42.3 = 3.2.3
> (many times rebooted for testing with first and second kernels).
> See bug https://bugzilla.redhat.com/show_bug.cgi?id=789659
>
> lsmod:
> Module Size Used by
> nvidia 10778232 40
> i2c_core 28123 1 nvidia
> 8139too 32490 0
> mii 13311 1 8139too
>
> dmesg:
> 8139too: 8139too Fast Ethernet driver 0.9.28
> 8139too 0000:01:02.0: PCI INT A -> GSI 22 (level, low) -> IRQ 22
> 8139too 0000:01:02.0: eth0: RealTek RTL8139 at , IRQ 22
> 8139too 0000:01:02.0: eth0: link up, 100Mbps, full-duplex, lpa 0x41E1
>
> For testing I selected fastest for me download mirrors of FreeBSD and Ubuntu,
> also I tested download speed from site speedtest.tele2.net.
>
> For these sites download speed with 3.1 kernels (and older) is about 11 MB/s
> but with 3.2.x kernels - limited 5.5 MB/s and for some sites still approximately
> the same as with 3.1 kernels (see bug mentioned above).
>

MB/s means MBytes or Mbits ?

> Also I want to pay attention that limited speed stays constant - always
> 5.5 MB/s with straight line on traffic plotter as if was network bandwidth shaping.
> With 3.1 kernels this never happens - speed can vary in some ranges
> but at maximum it is about 11 MB/s, no limitations such as 5.5 MB/s.
>

Could you post "netstat -s" result ?