unanswered requests from local host, high load

[Splitice]

I'm suprised you need so many workers. 

Sent from my iPod

On 29/10/2010, at 12:49 AM, Carsten Otto <otto at informatik.rwth-aachen.de> wrote:

> Dear list,
> 
> I'm running a public mirror server which currently handles about
> 5 GBit/sec with 15.000 concurrent connections and 1400 requests/second.
> We only serve static files and basically all served files are in RAM
> (e.g. the current Mozilla Firefox update).
> 
> In high load scenarios nginx sometimes fails to answer simple requests
> in time, even when they originate from localhost. According to
> SmokePing's "HTTP ping", which just GETs/HEADs the static index.html
> file, the time needed for this answer changes dramatically and packet
> loss is involved with up to 17% when the problems occur.
> 
> The Apache running in the background did not have this problem for
> queries from localhost. When considering external queries (another
> instance of SmokePing), I see gaps (100% packet loss) for both Apache
> and nginx, where nginx also has packet loss up to 20% and higher
> response times around that time.
> 
> If you want I can provide the four snippets of SmokePing graphs.
> 
> Configuration:
> nginx 0.8.53, 64 workers, no keepalive, 5000 worker connections, epoll,
> sendfile, tcp_nodelay
> Linux 2.6.26 (Debian), max 131072 open files
> two quadcore Xeons, 60 GByte DDR3, Intel 10 GBit NIC
> 10 TByte StorageTek disk backend
> 
> In case you need further information, I'm happy to provide it.
> 
> I just increased to 96 workers (as I already wanted, I accidently
> reverted that config today), let's see what happens...
> 
> Best regards,
> -- 
> Carsten Otto           otto at informatik.rwth-aachen.de
> LuFG Informatik 2      http://verify.rwth-aachen.de/otto/
> RWTH Aachen            phone: +49 241 80-21211
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