Re: Re: Re: Re: Re: Re: limited network bandwidth with 3.2.x kernels

Eric Dumazet
2012-02-15T06:07:00Z

Le mercredi 15 février 2012 à 01:03 -0500, Neal Cardwell a écrit :
> There are some potentially interesting differences in sysctl values:
>
> > diff -u /tmp/sysctl-a-3.1.txt /tmp/sysctl-a-3.2.txt | grep mem_def
> -net.core.wmem_default = 114688
> -net.core.rmem_default = 114688
> +net.core.wmem_default = 163840
> +net.core.rmem_default = 163840
>
> Can you please try running this as root on the 3.2 kernel and then see
> what sort of performance you get:
>
> sysctl net.core.rmem_default=114688
>
> This should make the 3.2 config closer to the 3.1 config. Should be
> interesting to see if the behavior is more similar when that happens.
>
> neal

These changes are normal, since skb truesize now include shared_info.

By the way, these params are not used for tcp streams.

This is why I asked netstat -s values, to check if we had drops because
of truesize limits.

Its not the case here since skb are not too fat (as some NICS can do,
using a full PAGE to hold a single 1500 bytes frams)