# Tuning Nginx as a Load Balancer

**URL:** <https://www.ruby-forum.com/t/tuning-nginx-as-a-load-balancer/191518>\
**Category:** NGINX\
**Created:** [July 13, 2010, 7:14pm UTC](https://www.ruby-forum.com/t/tuning-nginx-as-a-load-balancer/191518 "2010-07-13T19:14:50Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![WSandrew\_L](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/d07c76/32.png) [@WSandrew\_L](https://www.ruby-forum.com/u/WSandrew_L)\
**Post date:** [July 13, 2010, 7:14pm UTC](https://www.ruby-forum.com/t/tuning-nginx-as-a-load-balancer/191518/1 "2010-07-13T19:14:50Z")

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I’m running the 0.7 branch as the front door to 6 machines running  
nginx + passenger. The two workers (two core machine) are using a  
modest amount of CPU but I am still seeing spikes in my queue time  
metric. I’ve patched my instance to add a X\_REQUEST\_START header  
similar to this [Add a 'start\_time' variable to nginx 0.8.33 to support an X-REQUEST-START header. This header is used by New Relic RPM to record queue time. · GitHub](http://gist.github.com/318681)

According to my metrics, [Skitch | Evernote](http://skitch.com/waloeiii/dcj79/queue),  
somewhere around 200-250ms of each request is spent in ‘queue time’.  
My site runs 100% under SSL so a large portion of that is the SSL  
negotiation, but I think there is room to improve. These machines are  
all in ec2’s cloud with latencies \< 1ms and plenty of spare capacity  
so I’m pretty convinced that my load-balancer just needs some  
tweaking. My nginx.conf for the load-balancer is here:  
[nginx.conf · GitHub](http://gist.github.com/474180)

The load-balancing instance has 1.7GB of RAM, however over 1.5GB is  
free. Can I change some of the settings to allow nginx to keep more  
requests off the disk without opening my self up to possible denial of  
service? iostat/vmstat does show pretty consistent writes to the disk,  
but nothing like maxing it out. The X-REQUEST-START is only tracked on  
GET requests as well so slow client uploads should not be throwing off  
the numbers.

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<div class="post-metadata">

**Author:** ![WSandrew\_L](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/d07c76/32.png) [@WSandrew\_L](https://www.ruby-forum.com/u/WSandrew_L)\
**Post date:** [July 13, 2010, 8:13pm UTC](https://www.ruby-forum.com/t/tuning-nginx-as-a-load-balancer/191518/2 "2010-07-13T20:13:23Z")

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Turning on the SSL cache has been a good win so far.

ssl\_session\_cache shared:SSL:10m;  
ssl\_session\_timeout 5m; # default, included for completeness

On Tue, Jul 13, 2010 at 10:13 AM, W. Andrew Loe III