Visible to Intel only — GUID: nhx1483059478301
Ixiasoft
Visible to Intel only — GUID: nhx1483059478301
Ixiasoft
8.3.4.4. Bandwidth and Saturation
Encoding Bandwidth Values
The QoS bandwidth setting is frequency-dependent. Low-frequency masters require a larger value to achieve the same bandwidth as higher frequency masters.
You can calculate the register value for a bandwidth as follows:
*I_main_QosGenerator_Bandwidth = ( bandwidth / frequency ) * 256
where bandwidth is in MBps and frequency is in MHz.
For example, to configure the FPGA-to-SDRAM 0 QoS generator for a bandwidth of 1000 MBps at 200 MHz, calculate the register value as follows:
fpga2sdram0_axi128_I_main_QosGenerator_Bandwidth = ( 1000 / 200 ) * 256 = 1280.
Encoding Saturation Values
The QoS saturation represents the period of time that the master bandwidth is evaluated. The saturation value represents units of 16 bytes of data transferred. For example a 64-bit master that should have the bandwidth re-evaluated every 100 clock cycles would use a saturation setting of 100 cycles * 8 bytes / 16 bytes =50
The saturation register controls the number of bytes that the initiator can transmit at full speed before the limiter or regulator takes effect. The register encodes the byte count as a multiple of 16 bytes. Therefore you can calculate the register value as follows:
*I_main_QosGenerator_Saturation = nbytes / 16
For example, to let the MPU initiator send 64 bytes at full speed, calculate the register value as follows:
mpu_m1_I_main_QosGenerator_Saturation = 64 / 16 = 4