[BUG,REGRESSION?] 3.11.6+,3.12: GbE iface rate drops to few KB/s

[arno@natisbad.org (Arnaud Ebalard)]

Hi eric,

Eric Dumazet <eric.dumazet@gmail.com> writes:

>> > I tested it on my RN2120 (2-core armada XP): I got no problem and the
>> > link saturated w/ apache, nginx and netperf. Good work!
>> 
>> Great, thanks for your tests Arnaud. I forgot to mention that all my
>> tests this evening involved this patch as well.
>
> Now you might try to set a lower value
> for /proc/sys/net/ipv4/tcp_limit_output_bytes

On the RN2120, for a file served from /run/shm (for apache and nginx):

          Apache     nginx       netperf
131072:  102 MB/s   112 MB/s   941.11 Mb/s
 65536:  102 MB/s   112 MB/s   935.97 Mb/s
 32768:  101 MB/s   105 MB/s   940.49 Mb/s
 16384:   94 MB/s    90 MB/s   770.07 Mb/s
  8192:   83 MB/s    66 MB/s   556.79 Mb/s

On the RN102, this time for apache and nginx, the file is served from
disks (ext4/lvm/raid1):

          Apache     nginx       netperf
131072:  66 MB/s   105 MB/s   925.63 Mb/s
 65536:  59 MB/s   105 MB/s   862.55 Mb/s
 32768:  62 MB/s   105 MB/s   918.99 Mb/s
 16384:  65 MB/s   105 MB/s   927.71 Mb/s
  8192:  60 MB/s   104 MB/s   915.63 Mb/s

Values above are for a single flow though.

Cheers,

a+