During a recent webinar, I believe I heard it claimed that there's less than 5% overhead for running the collector. Just how is that computed? There's whatever the impact is running a workload after "vpp start" and that does seem relatively minimal (I say seems, because I'm using a desktop not a dedicated server) but ...
- Just what resources are being used (large memory array? temp file(s)??).
- Just what is the impact of vpp stop ? It seems to spawn a very CPU intensive python task ... which runs for several minutes ... that seems likely to have noticable impact...
- Similarly for vpp upload (is that "just" a ftp (scp?) transfer?
I would like to be able to deploy vpp to production servers ... but I expect significant pushback if there's periodic impact to running services (obviously, we'll have to do our own measurements) ... if there are ways to mitigate impact (is there a vpp stop internal step which would just store the file, and allow for processing (whatever is going on) to be done off the SUT? Can it be configured to do its work with lower impact (perhaps taking longer to execute ... if/when we're in production it won't matter how long it takes for the results to become available...)
is there some way to apply vpp to itself? that is to use another instance to monitor what's going on during the vpp stop? That might provide compelling evidence of minimal impact ... if, it is, in fact, minimal during this phase of processing.
ON an unrelated note, I'm more than a little disappointed that I didn't get any responses from my Ubuntu19 installation question ...
The collection overhead refers to the potential slowdown your workload/system will incur while data collection is active. In VPP, this refers to the time period starting when the "vpp-collect start" command is executed and ending when you invoke "vpp-collect stop". The overhead of the "stop" and "upload" operations are not considered part of the collection overhead.
When you start data collection, you can specify the --nofinalize option to defer the finalization step to the VPP server. This will reduce the processing time of the "stop" command.
The "upload" command transfer the collection results to the VPP server. This is similar to an SCP operation.
There can be only one VPP data collection session running at a given time on a given machine. Therefore, you cannot apply VPP to itself. However, the --nofinalize option mentioned above should address your concerns with regard to the "stop" command processing time.