[squid-users] Need clarifications on custom log timestamps

[Alex Rousskov]

On 2025-02-17 10:02, BENJAMIN DELANNOY wrote:

> I try to figure out what is exactly measured with the <pt & <tt timings. 
> I don't get what are the difference between them, what is the difference 
> between "peer response time" & "time spent forwarding to origin 
> servers", 

Have you seen %<pt and %<tt descriptions at [1]? %<tt description was 
updated in August 2024, and squid.conf.documented in Squid v6 and 
earlier does not have those documentation updates (and the corresponding 
bug fixes)...

[1] http://www.squid-cache.org/Doc/config/logformat/


> what is the "last I/O with the last peer", etc.

When forwarding a single client request, Squid may talk to multiple 
cache_peer and origin server addresses (collectively called "peers"). 
Talking to a given peer may include multiple socket reading and writing 
(i.e. I/O) events. Does this clarify?



> For information, I aim to calculate the time spent on the client-side & 
> by squid processing time,  excluding the server-side time spent (=what I 
> don't manage).

This kind of calculation is a common need. Please keep in mind that 
Squid may spend time on the client side (e.g., awaiting the next request 
body byte) while also spending time on the server side (e.g., awaiting 
the next response body byte), complicating things.

If existing %codes are not enough, please detail your needs in terms of 
events that Squid can recognize (e.g., receiving the first response 
header byte or sending the last request body byte).


HTH,

Alex.




> We do not use squid for caching but only for http & ssl proxy/filtering.
> 
> Thanks a lot !
> 
> 
> Cordialement, Regards,
> 
> 
> Benjamin DELANNOY
> 
> Cloud Network Engineer
> 
> NETWORK SOLUTIONS - GTDP
> 
> Mobile +33 (0)6 16 98 23 72
> 
> 
> 135 rue Sadi Carnot • CS 00001 • 59790 Ronchin • FRANCE
> 
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> 
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> 
> 
> 
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