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

[Christian Schmid]

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
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