RE: [squid-users] Slow Squid

You state that response time is slow, but not which. Is that average,
misses, near misses or hits? What are each of the other rates?

Where are you getting your CPU Utilization numbers from? (top, squidclient
mrg:info, MRTG)

What is your cache_mem line set to?

How much bandwidth do you have available? How much is being used?

One thing that really bit me was over-use of the url_regex acl combined with
fairly complex regular expressions. That's not likely to be the problem
here, but it might be something to look into.

Chris

-----Original Message-----
From: Sturgis, Grant [mailto:Grant.Sturgis@arraybiopharma.com]
Sent: Monday, November 15, 2004 10:24 AM
To: squid-users@squid-cache.org
Subject: [squid-users] Slow Squid

Greetings List,

I am writing for ideas on how I can increase the performance of my squid
cache.

I am running:

RHEL ES 3.0
cache_dir aufs on ext2
squid-2.5.STABLE3-6.3E
adzapper version 3.3 with wrapzap
Two cache_dirs totalling 42.4 GB

The hardware is:

Dell PE 1650
2-Intel PIII 1133 MHz
4 GB RAM

The symptom is that during our peak utilization periods, when HTTP
requests get over about 750/min, the response time gets very slow, over
800 ms or so. I understand that squid is single threaded, but we are
running a number of the redirector processes and it seems that the CPU
workload is distributed fairly well. This is determined by examining
/proc/stat with MRTG. Neither CPU seems to reach above 55% utilization
so I do not think the system is CPU bound.

One thing that is concerning:

[root@proxy squid]# free -m
             total used free shared buffers
cached
Mem: 3778 3756 22 0 472
2154
-/+ buffers/cache: 1129 2649
Swap: 8997 715 8282

Do you think this is significant? Should I adjust squid.conf to reduce
this memory usage?

Also, I do understand that reiserfs is a recommended file system over
ext2; do you think it will make a large difference to change this?

Any suggestions for things I can do to determine why my cache is slow or
how to make improvements in performance?

Thank you in advance,

Grant

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Received on Mon Nov 15 2004 - 15:33:47 MST