Requests per second slower when using nginx for load balancing
- by Ed Eliot
I've set up nginx as a load balancer that reverse proxies requests to 2 Apache servers. I've benchmarked the setup with ab and am getting approx 35 requests per second with requests distributed between the 2 backend servers (not using ip_hash). What is confusing me is that if I query either of the backend servers directly via ab I get around 50 requests per second.
I've experimented with a number of different values in ab the most common being 1000 requests with 100 concurrent connections.
Any idea why traffic distributed across 2 servers would result in fewer requests per second than hitting either directly?
Additional info:
I've experimented with worker_processes values of between 1 and 8, worker_connections between 1024 and 8092 and have also tried keepalive 0 and 65.
My main conf currently looks like this:
user www-data;
worker_processes 1;
error_log /var/log/nginx/error.log;
pid /var/run/nginx.pid;
worker_rlimit_nofile 8192;
events {
worker_connections 2048;
use epoll;
}
http {
include /etc/nginx/mime.types;
sendfile on;
keepalive_timeout 0;
tcp_nodelay on;
gzip on;
gzip_disable "MSIE [1-6]\.(?!.*SV1)";
include /etc/nginx/conf.d/*.conf;
include /etc/nginx/sites-enabled/*;
}
I've got one virtual host (in sites available) that redirects everything under / to 2 backends across a local network.
