B.5 Calculations

B.5.1 24-Hour Profile

The 24-hour profile consists of 24 values that correspond to each hour of the day (0 to 23). Each value is calculated by taking the peak value for that specific hour over the number of monitoring days.

Example

Consider a system monitored for 3 days. The following chart presents the data set for its Processor workload, and the calculated 24-hour profile:

Table B-4 Processor Workload Data Set

Hour

Day 1

Day 2

Day 3

24-Hour Profile

0

200

300

500

500

1

300

300

250

300

2

300

400

450

450

3

700

250

350

750

4

500

500

500

500

5

600

400

500

600

6

500

550

750

750

7

400

600

800

800

8

500

300

250

500

9

450

350

640

640

10

200

240

340

340

11

300

600

+60

650

12

300

-

-

300

13

550

340

850

850

14

440

500

600

600

15

800

540

600

800

16

750

260

430

750

17

500

640

450

640

18

600

200

350

600

19

300

250

650

650

20

200

300

200

300

21

250

350

400

400

22

600

250

350

600

23

500

650

750

750

B.5.2 Dual-Core and Multi-Core Machines

PlateSpin Recon considers and treats dual-core or multi-core machine as two-processor or x-processor machines.

B.5.3 Hyper-Threading

The effect of hyper-threading is controlled by two configuration parameters: Aggregate Instance Function (SUM, AVG) and Hyper-threading Normalization Factor (1 – 2). The default value for aggregate instance function is AVG, and the normalization factor is set to 1.25. These values can be configured in the advanced settings under Tools > Options.

PlateSpin Recon collects each individual processor instance’s utilization values at a given time and then calculates the processor utilization based on the aggregate function. If the aggregate function is SUM, then the physical processor utilization is the sum of all logical processor instances’ utilization. If the aggregate function is AVG, then the physical processor utilization would be average of all logical processor instances’ utilization.

Example

Consider a system with single-core processor with hyper-threading enabled at p MHz speed. For a given period of time, PlateSpin Recon calculates the percentile utilization values for 24H profile values of instance X and Y as follows.

{X}= {X1, X2, Xi…..X24}, Xi is the utilization of the processor instance X at hour i.

{Y}= {Y1, Y2, Yi…..Y24}, Yi is the utilization of the processor instance Y at hour i.

Table B-5 Aggregate Function Calculations

(Aggregate Function, Normalization Factor)

( SUM, f )

( AVG, f )

Reports: Peak %

Max { X + Y }

Max { (X + Y) / 2 }

Reports: Peak (MHz)

Max { X + Y } * (1/100) * p * f

Max { (X+Y)/2 } * (1/100) * p * f

CPM: Workload calculation

{X+Y} * (1/100) * p * f

{(X+Y)/2} * (1/100) * p * f

B.5.4 Effective Speed

PlateSpin Recon takes both number of cores and hyper-threading into account when calculating the effective speed of a machine.

Example:

Server template specification: 2 x 3000 GHz, dual core, and hyper-threading enabled

Number of processors: P = 2 * 2 = 4

Processor capacity: C = 3000 GHz

Hyper-threading normalization factor: n = 1.25 (default value)

Scaling factor: A(p) = P / { 1 + ä (P-1) } , where ä = 0.05

A(p) = 4 / { 1 + 0.05 * 3} = 3.4782

Effective speed = A(p) * C * n = 3.4782 * 3000 * 1.25 = 13043 MHz

B.5.5 Power and Cooling

Energy Use (kWh/yr) = Power Usage (W) x Server Derating Factor x Number of hours in a year (8760) / 1000

Heat Dissipation (BTU/yr) = Energy Use (kWh/yr) x 3.41

Annual Energy Cost = Energy Cost per kWh x Energy Use (kWh/yr)

B.5.6 CO2 Emission

Energy Use (kWh/yr) = Power Usage (W) x Server Derating Factor x Number of hours in a year (8760) / 1000

CO2 Emission (1b/yr) = Energy Use (kWh/yr) x 1.54

The constant factor of 1.54 has been considered as per the standards.