Improving Site Performance:
1. Disable all caching in the site and do benchmark for anon user
2. Benchmark for auth user for a particular page
3. Check logs to see if any notice or error is happening in the site. Solve the issue and notice BM
4. Disable unwanted modules if any and do another benchmark. Note the diff.
5. Modify or update apache or mysql setting minor if any to see noticiable change in benchmark
6. Optimize PHP and see if noticeable difference occurs
7. Install Devel and check queries and page rendering times
8. Optimize queries or fix issues if possible to resolve queries or rendering times
9. Install caching modules one by one and check the benchmark and also see page execution times with devel.
Benchmarking using: ab - Apache HTTP server benchmarking tool
ab is a tool for benchmarking your Apache Hypertext Transfer Protocol (HTTP) server. It is designed to give you an impression of how your current Apache installation performs. This especially shows you how many requests per second your Apache installation is capable of serving.
Using Apache bench:
Suppose we want to see how fast example.net can handle 100 requests, with a maximum of 5 requests running concurrently:
ab -n 100 -c 5 http://www.example.net/drupal/index.php > drupal_example_v3.log Options:
-n requests
Number of requests to perform for the benchmarking session. The default is to just perform a single request which usually leads to non-representative benchmarking results.
-c concurrency
Number of multiple requests to perform at a time. Default is one request at a time.
The data collected are stored in drupal_example_v3.log
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Source:
http://london2011.drupal.org/conference/sessions/damn-quick-drupal-how-m...
http://www.expresstut.com/content/solving-drupal-performance-problem
http://xerosphere.net/optimizing-apc-for-drupal
http://www.mysqlperformanceblog.com/2007/11/01/innodb-performance-optimi...
http://ratatosk.net/drupal/tutorials/debugging-drupal.html
http://cloudinservice.com/tune-apache-performance-using-mpm-prefork-module/
Ab Benchmarking: http://drupal.org/node/659974
http://ma.juii.net/blog/apache2-php-handler
http://www.cyberciti.biz/tips/howto-performance-benchmarks-a-web-server....
http://www.petefreitag.com/item/689.cfm