The Importance of Caching
Submitted by david on Fri, 2011-02-11 10:53
Even a minimal amount of caching can greatly boost your site’s performance. Here’s a comparison on dmwl.net of no caching vs. drupal:
Connection Times (in milliseconds)
No Caching
| min | mean | [+/-sd] | median | max | |
|---|---|---|---|---|---|
| Connect: | 0 | 1 | 0.4 | 1 | 6 |
| Processing: | 585 | 3922 | 2318.1 | 3677 | 16137 |
| Waiting: | 556 | 3592 | 2247.3 | 3283 | 15278 |
| Total: | 586 | 3922 | 2318.1 | 3677 | 16137 |
Basic Caching
| min | mean | [+/-sd] |
median |
max | |
|---|---|---|---|---|---|
| Connect: | 1 | 1 | 0.4 | 1 | 6 |
| Processing: | 218 | 745 | 460.8 | 590 | 3516 |
| Waiting: | 216 | 736 | 446.1 | 588 | 3515 |
| Total: | 219 | 746 | 460.9 | 591 | 3517 |
Percentage of the requests served within a certain time (in milliseconds)
No Caching
- 50% 3677
- 66% 4539
- 75% 5149
- 80% 5493
- 90% 6500
- 95% 7354
- 98% 11320
- 99% 13797
- 100% 16137 (longest request)
Basic Caching
- 50% 591
- 66% 761
- 75% 945
- 80% 1027
- 90% 1360
- 95% 1720
- 98% 2214
- 99% 2313
- 100% 3517 (longest request)
Test Setup
ApacheBench was used with the following parameters:
ab -c 10 -n 1000 http://dmwl.net/index.php
(1000 requests, 10 concurrent requests) from a host remote to the server that can get 4MB/s sustained transfers.
Summary
I knew that caching would make a difference, but I wasn’t expecting a 14 second difference. Even minimal caching helps systems under load.
