RE: [squid-users] Strange performance effects on squid during off peak hours

Hi Amos!

Thanks for your feedback.

> Squid is still largely IO event driven. If the network IO is less than
> say 3-4 req/sec Squid can have a queue of things waiting to happen which
> get delayed a long time (hundreds of ms) waiting to be kicked off.
> Your overview seems to show that behaviour clearly.
>
> There have been some small improvements and fixes to several of the
> lagging things but I think its still there in even the latest Squid.

Here the Hit/s statistics on this specific server for the time:
+------+-------+-------+
| h | allHPS| cssART|
+------+-------+-------+
| 0 | 48.34 | 0.016 |
| 1 | 49.80 | 0.015 |
| 2 | 49.01 | 0.015 |
| 3 | 47.08 | 0.018 |
| 4 | 17.34 | 0.024 |
| 5 | 4.00 | 0.042 |
| 6 | 0.52 | 0.054 |
| 7 | 9.02 | 0.034 |
| 8 | 7.18 | 0.038 |
| 9 | 8.25 | 0.035 |
| 10 | 9.45 | 0.034 |
| 11 | 14.71 | 0.030 |
| 12 | 23.94 | 0.023 |
| 13 | 31.04 | 0.021 |
| 14 | 35.02 | 0.020 |
| 15 | 38.87 | 0.019 |
| 16 | 40.92 | 0.019 |
| 17 | 43.39 | 0.017 |
| 18 | 45.62 | 0.016 |
| 19 | 47.58 | 0.017 |
| 20 | 51.91 | 0.014 |
| 21 | 53.65 | 0.014 |
| 22 | 40.87 | 0.016 |
| 23 | 47.40 | 0.016 |
+------+-------+-------+

So to summarize it: we need to keep the number of hits above 30 hits/s for squid, so that we get an acceptable Response time.

I believe it will need some convincing of management to get this assumption tested in production ;)

One other Question: is squid 3.1 "better" in this respect than 3.0?

Thanks,
        Martin

This message and the information contained herein is proprietary and confidential and subject to the Amdocs policy statement,
you may review at http://www.amdocs.com/email_disclaimer.asp
Received on Wed Sep 15 2010 - 19:53:18 MDT