Table 23: Taf Impact On Shared Buffer Average Utilization Calculation - Alcatel-Lucent 7210 SAS-R6 OS Quality Of Service Manual

used to determine the portion of the shared buffer instantaneous utilization and the previous shared
buffer average utilization used to calculate the new shared buffer average utilization. To derive the
new shared buffer average utilization, the buffer pool takes a portion of the previous shared buffer
average and adds it to the inverse portion of the instantaneous shared buffer utilization (SBU). The
formula used to calculated the average shared buffer utilization is:
where:
SBAU
SBAU
SBU = The instantaneous shared buffer utilization
TAF = The time average factor
Table 23
instantaneous SBU and the previous SBAU (SBAU
(SBAU

Table 23: TAF Impact on Shared Buffer Average Utilization Calculation

TAF
0
1
2
3
4
5
6
7
8
7210 SAS-X and 7210 SAS-R6 OS Quality of Service Guide
⎛
SBAU = SBU
⎝
n
= Shared buffer average utilization for event n
n
= Shared buffer average utilization for event (n-1)
n-1
shows the effect the allowed values of TAF have on the relative weighting of the
).
n
TAF Equates
2
To
0 1
2
1 2
2
2 4
2
3 8
2
4
16
2
5 32
2
6 64
2
7 128
2
8 256
2
⎛
⎞
1 2
× ×
⎜
----------- - -------------------- -
+ SBAU
⎠
n 1 –
TAF ⎝
2
n-1)
Shared Buffer
Instantaneous
Utilization Portion
1/1 (1)
1/2 (0.5)
1/4 (0.25)
1/8 (0.125)
1/16 (0.0625)
1/32 (0.03125)
1/64 (0.015625)
1/128 (0.0078125)
1/256 (0.00390625)
⎞
TAF
– 1
⎟
TAF ⎠
2
has on the calculating the current SBAU
Shared Buffer Average
Utilization Portion
0 (0)
1/2 (0.5)
3/4 (0.75)
7/8 (0.875)
15/16 (0.9375)
31/32 (0.96875)
63/64 (0.984375)
127/128 (0.9921875)
255/256 (0.99609375)
QoS Policies
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