June 2001
Intermediate to advanced
320 pages
9h 18m
English
Content preview from Web Caching
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Service Times
Table A-11 shows the mean and median service times for different types of requests. The type is taken directly from the fourth field of Squid’s access.log file. The three-digit number following the slash is the HTTP status code. Here I show only 200 (OK) and 304 (Not Modified) replies.
Table A-11. Mean and Median Service Times by Cache Result (IRCache Data)
| Type | Mean (sec) | Median (sec) |
|---|---|---|
| TCP_REFRESH_HIT/200 | 5.165 | 0.281 |
| TCP_MISS/200 | 4.590 | 0.466 |
| TCP_REFRESH_MISS/200 | 4.091 | 0.468 |
| TCP_CLIENT_REFRESH_MISS/200 | 1.889 | 0.215 |
| TCP_HIT/200 | 1.819 | 0.050 |
| TCP_MISS/304 | 1.151 | 0.294 |
| TCP_REFRESH_HIT/304 | 1.107 | 0.219 |
| TCP_IMS_HIT/304 | 0.102 | 0.042 |
The string before the slash indicates how the cache handled the
request. TCP_MISS means the object wasn’t found in the cache at
all. TCP_HIT indicates an unvalidated cache hit. TCP_IMS_HIT
occurs when Squid receives an
If-modified-since request and returns a 304
(Not Modified) reply immediately because the response is fresh
according to the local configuration. TCP_CLIENT_REFRESH_MISS
means that the user-agent sent the no-cache
directive. TCP_REFRESH_HIT occurs when Squid validates its
cached response and learns that the object hasn’t changed. If
the client’s request includes an If-modified-since header, Squid returns the
304 message. Otherwise, it sends the entire object, and the
status is 200. Finally, TCP_REFRESH_MISS means Squid sent
a validation request to the origin server, and the cached
object was out-of-date.
This data is derived from the second field of Squid’s access.log ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.