System can't take more than 5k req /sec

Jason Price japrice at
Tue May 13 15:31:16 CEST 2014

Private message requesting TCP tuning.  For the record, these are
draft numbers and very tightly tied to our use case, so they should
not be copied blindly.

somaxconn is 512
txqueuelen is 5000
netdev_max_backlog is 5000
tcp_max_syn_backlog is 4096
enable tcp_tw_recycle
enable tcp_tw_reuse

On Tue, May 13, 2014 at 6:45 AM, Γιάννης Καραγιαννίδης
<gkaragiannidis at> wrote:
> Could you please give us some more information about your
> TCP tuning?
> Regards
> Yiannis
> -----Original Message-----
> From: at [ at] On Behalf Of Jason Price
> Sent: Tuesday, May 13, 2014 12:33 AM
> To: Norberto Meijome
> Cc: varnish-misc at
> Subject: Re: System can't take more than 5k req /sec
> So, through some TCP tuning we've been able to get to 20k/s.  Though I needed to get up to 8k threads per pool.
> Many docs say 'Don't go more than 4k threads'.  Can someone explain that?  Anyone have experience with 8-10k threads?
> --Jason
> On Tue, Apr 29, 2014 at 10:41 PM, Jason Price <japrice at> wrote:
>> On Tuesday, April 29, 2014, Norberto Meijome <numard at> wrote:
>>> Have you ruled out AWS limits? Putting varnish aside for a minute,
>>> can you handle 5k/sec TCP conns with something like nginx +static files.?
>> This is an excellent question.  I'll see what kind of answer I'll get to it.
>> -Jason
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