Re: How Squid Computes HTTP All Median Svc Time

On Thursday 14 August 2003 12.06, atit jariwala wrote:
> Hello Squid Developers,
> I am using Squid 2.5 Stable2 on redhat Linux 7.* .
> I want to know how squid computes HTTP All Median Svc Time for 5
> minute and 60 minute.
> I gone through code of stat.c & StatHist.c but still not get
> picture clear at all.
> Please Can any one tell me how squid calculates it and what r the
> other parameters taken into consideration while counting it.

Squid keeps statistics for each minute (last 60 minutes) and each hour
(last 3 days/72 hours). This statistics includes histograms of the
service time for requests from start to when this statistics was
taken (minutes / hours ago depending on which table is accessed).

The statHistDeltaMedian compares two histograms and gives a close
estimate of the median value based on the delta between the two
histograms (delta == amount of change from one to the other).

> & one more thing to ask:
> If i m sending 2 request each of 20 MB download and CACHE_MISS as
> well, does it affect my Median HTTP Svc Time for that duration if
> So how?

The service time is calculated when the request finishes and is logged
in access.log. Long downloads have a long service time.

However, as the calculation is a median it should be quite immune to
such extremes compared to a average calculation.

Regards
Henrik
Received on Thu Aug 14 2003 - 23:59:06 MDT