Nginx + PHP-FPM Using CPU and Not RAM - php

Question

I am doing load testing on an Nginx Server and I am having an issue where my CPU hits 100% but only 50% of my ram is being utilized. The server is this:
2 vCPU
2 GB of RAM
40GB SSD Drive
Rackspace High Performance Server
This is my Nginx Config
worker_processes 2;
error_log /var/log/nginx/error.log crit;
pid /var/run/nginx.pid;
events {
worker_connections 1524;
use epoll;
multi_accept on;
}
http {
include /etc/nginx/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 /var/log/nginx/access.log main;
access_log off;
# Sendfile copies data between one FD and other from within the kernel.
# More efficient than read() + write(), since the requires transferring data to and from the user space.
sendfile on;
# Tcp_nopush causes nginx to attempt to send its HTTP response head in one packet,
# instead of using partial frames. This is useful for prepending headers before calling sendfile,
# or for throughput optimization.
tcp_nopush on;
# don't buffer data-sends (disable Nagle algorithm). Good for sending frequent small bursts of data in real time.
tcp_nodelay on;
# allow the server to close the connection after a client stops responding. Frees up socket-associated memory.
reset_timedout_connection on;
#keepalive_timeout 0;
keepalive_timeout 65;
# send the client a "request timed out" if the body is not loaded by this time. Default 60.
client_body_timeout 10;
# If the client stops reading data, free up the stale client connection after this much time. Default 60.
send_timeout 2;
open_file_cache max=200000 inactive=20s;
open_file_cache_valid 30s;
open_file_cache_min_uses 2;
open_file_cache_errors on;
gzip on;
server_tokens off;
client_max_body_size 20m;
client_body_buffer_size 128k;
client_max_body_size 20m;
client_body_buffer_size 128k;
gzip_min_length 10240;
gzip_proxied expired no-cache no-store private auth;
gzip_types text/plain text/css text/xml text/javascript application/x-javascript application/xml;
gzip_disable "MSIE [1-6]\.";
# Load config files from the /etc/nginx/conf.d directory
# The default server is in conf.d/default.conf
fastcgi_cache_path /var/cache/nginx levels=1:2 keys_zone=microcache:10m max_size=1000m inactive=60m;
include /etc/nginx/conf.d/*.conf;
include /etc/nginx/sites-enabled/*;
}
Kernal additions in /etc/sysctl.conf
# Increase system IP port limits to allow for more connections
net.ipv4.ip_local_port_range = 2000 65000
net.ipv4.tcp_window_scaling = 1
# number of packets to keep in backlog before the kernel starts dropping them
net.ipv4.tcp_max_syn_backlog = 3240000
# increase socket listen backlog
net.core.somaxconn = 3240000
net.ipv4.tcp_max_tw_buckets = 1440000
# Increase TCP buffer sizes
net.core.rmem_default = 8388608
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.ipv4.tcp_rmem = 4096 87380 16777216
net.ipv4.tcp_wmem = 4096 65536 16777216
net.ipv4.tcp_congestion_control = cubic
Example VHost Config with PHP-FPM
server {
listen 80;
server_name www.example.com;
location / {
root /data/sites/example.com/public_html;
index index.php index.html index.htm;
try_files $uri $uri/ /index.php?rt=$uri&$args;
}
location ~ \.php {
root /data/sites/example.com/public_html;
fastcgi_pass unix:/var/run/php-fpm/php-fpm.sock;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
fastcgi_param SCRIPT_NAME $fastcgi_script_name;
fastcgi_index index.php;
fastcgi_param PATH_INFO $fastcgi_script_name;
fastcgi_param ENV production;
include fastcgi_params;
}
}
The server can handle about 60 active SBU connections clicking around, or about 300 request per second. Is the fact that is not fully utilizing RAM and more CPU a bad thing? Can I optimize this further?