bad performance with static files + keepalive

[mex]

Hi List,

i have a strange performance-issue on a server that serves
static-files only (http + https), if files are bigger than 5k:

- rps drops from 6500 rps (empty file) to 13 rps when requesting a file >
5k
- perftest with location /perftest/ is at 8000 rps (https) / 15000 rps
(http)
- perftest with empty.html is 6500 rps (https) / 13000 rps (http)
- perftest with 5k script.js is 1500 rps (https) / 12000 rps (http)
- perftest with 30k script.js is 13 rps (https) / 300 rps (http)
- beside that bad performance we have a lot of complaints of
slow servers and i can confirm that loading of these resouces takes up to 15
seconds

- OS is SLES11.2, system is a kvm virtual-machine, 2 cores, 1GB ram, 270mb
free, 420mb cached
- fresh reboot
- no iowait
- no shortage of ram
- error_log/debug shows nothing. 

what i played with so far, with no improvements:

- open_file_cache 
- keepalive_requests 10.....100000
- keepalive_timeout 
- sendfile/tcp_*
- various ssl_ciphers (PFS is not needed here)
- different nginx-version (os is 1.0.10, self-compiled is 1.4.2)

i'm scratching my head an am wondering: what did i missed?
there must be something ... on similar setup with debian/ssl 
we receive an average of 4000 rps for static files with
PFS-algos on.


ssl/config
-------------------------------------------------
worker_processes  2;

worker_rlimit_nofile 10000;

#error_log  /var/log/nginx/error.log;
#error_log  /var/log/nginx/error.log  notice;
#error_log  /var/log/nginx/error.log  info;

#pid        /var/run/nginx.pid;


events {
    worker_connections  1000;
    use epoll;
    multi_accept on;
}



http {
    include       mime.types;
    default_type  application/octet-stream;

    #log_format  main  '$remote_addr - $remote_user [$time_local] "$request"
'
    #                  '$status $body_bytes_sent "$http_referer" '
    #                  '"$http_user_agent" "$http_x_forwarded_for"';


#    access_log off;
    sendfile        on;
    tcp_nopush     on;
    tcp_nodelay on;

    send_timeout 15s;


    #keepalive_timeout  0s;
    keepalive_timeout  15s;
    keepalive_requests  10; 

    server_tokens off;

    open_file_cache max=1000 inactive=20s; 
    open_file_cache_valid    60s; 
    open_file_cache_min_uses 2;
    open_file_cache_errors   on;


}

server  {
    ...

  ssl_session_cache       shared:SSL:10m;
  ssl_session_timeout     1440m;
  ssl_protocols           SSLv3 TLSv1 TLSv1.1 TLSv1.2;
#  ssl_ciphers            
ECDHE-RSA-AES256-SHA384:AES256-SHA256:RC4:HIGH:!MD5:!aNULL:!EDH:!AESGCM;
#  ssl_ciphers RC4:HIGH:!aNULL:!MD5;
  #ssl_ciphers
ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-SHA384:ECD
HE-RSA-AES256-SHA384:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-SHA2
56:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-RC4-SHA:ECDHE-RSA-RC4-SHA:ECDH-ECDSA-RC4-SHA:ECDH-RSA-RC4-SHA:E
CDHE-RSA-AES256-SHA:RC4-SHA:HIGH:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!CBC:!EDH:!kEDH:!PSK:!SRP:!kECDH;

  ssl_prefer_server_ciphers on;

  ssl_ciphers HIGH:!aNULL:!MD5:!kEDH:!kECDH;


  location / {
    root /srv/htdocs/domain;
    expires 1w;

  }
  
  location /perftest {
     return 200; 
  }


regards & thanx in advance

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,244146,244146#msg-244146