The instantaneous vector size - in the stats segment, per-thread - is the best measure of how hard vpp is working.
It's not a linear function of the offered load, but for any given offered load / feature set you can model it with three segments: * Dead asleep: vector size < 3, offered load up to maybe 1 mpps’ worth of simple forwarding * Linear region: vector size increases smoothly as offered load increases, up a vector size of maybe 128 or so * Hit the wall: a slight increate in offered load causes a huge jump in the vector size, traffic loss, etc. HTH... Dave -----Original Message----- From: vpp-dev@lists.fd.io <vpp-dev@lists.fd.io> On Behalf Of Prashant Upadhyaya Sent: Friday, June 7, 2019 5:41 AM To: vpp-dev@lists.fd.io Subject: [vpp-dev] Approximate effective CPU utilization of VPP worker Hi, I understand that VPP workers poll so they are always at 100 % CPU. However, I want to get an estimate of what is the effective CPU utilization i.e. the amount which was spent in doing the work for packet processing. In the native applications, the crude way I used to employ was to take a time window of say 1 second and I already know how many cpu cycles it is worth, this acted as the denominator. Then in every packet poll, I used to count the cycles spent when the packet was actually brought in and processed. So empty polls were not counted in the used cycles. This acted like the numerator. When the window was exhausted, I used the numerator/denominator to get an approximation of effective CPU utilization of the worker. Is something like this already possible in VPP, I need to constantly monitor the effective CPU utilization of the worker at runtime to take some decisions and inform the system peers eg. to reduce sending traffic etc. Regards -Prashant
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