Re: BUG: Slowdown on 3000 socket-machines tracked down

Christian Schmid
2005-03-07T14:35:51Z

Ben Greear wrote:
>> Its a full-duplex. Its a download-service with 3000 downloaders all
>> over the world.
>
>
> So actually it's really mostly one-way traffic, ie in the download
> direction.
> Anything significant at all going upstream, other than ACKs, etc?

Not much. See on the graph. The red is the downstream ;)

>> Yes. send-buffer to 64 kbytes and receive buffer to 16 kbytes.
>
>
> With regard to this note in the 'man 7 socket' man page:
>
> NOTES
> Linux assumes that half of the send/receive buffer is used for
> internal kernel struc-
> tures; thus the sysctls are twice what can be observed on the wire.
>
> What value are you using for the sockopt call?

First I used 64 * 1024 but some months ago I checked with getsockopt and realized that it always
gives twice of the value back. So I just have done 64 * 512 ;)

Chris