Feature: Linear cps increase

[bklang]

This PR allows scaling up the CPS rate over time, linearly.

However, I'm not quite happy with it because the increment interval is hard-coded at 1 second. This means going from 5CPS to 35CPS can only happen in 30 seconds, which isn't terribly useful to watch the impact of growing CPS. The problem is SIPp, which re-uses the stats interval (-fd) setting to determine the CPS increase interval. The correct fix for this would be to create a separate interval argument to SIPp and use that. TBD.

[bklang]

See SIPp/sipp#107

[wdrexler]

Could you not just specify your CPS increase speed by using SIPp's -rate_increase option? "-rate_increase 30" would get you from 5 to 35 CPS in a second with -fd 1

[bklang]

@wdrexler The problem is that I want to increase more slowly. For example, I want to go from 10CPS to 20CPS over a period of 10 minutes, with 1 CPS increase each minute. To do that, I would have to set -fd 60s, which has the negative side effect of lowering the stats collection interval, since they share the setting.

[bklang]

@benlangfeld

[benlangfeld]

So SippyCup is now released with our usage of the SIPp API for this, and SIPp has merged it. We're now simply waiting for a new SIPp package to be released at https://launchpad.net/~taisph/+archive/ubuntu/sipp; I've contacted the PPA maintainer about this to check it will happen.

We're also waiting on #31 so that this PR can introduce changes necessary to ensure the correct version of the SIPp package gets installed.

Tick tock....