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Device Performance Optimization
PXR40 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor
33-2
•
Signal Processing Extension (SPE-APU)
•
Variable Length Encoding (VLE)
•
Compiler optimizations
Further factors that impact the overall application performance are the use of the intelligent peripherals:
•
Use of DMA rather than CPU to transfer data efficiently
•
Use of DMA service requests rather than CPU interrupts to avoid software polling:
•
Off-loading tasks from the CPU to the eTPU2 or eDMA
•
Careful allocation of cache usage for code & data ranges, particularly when using with external
memories.
Different items in this list will have different performance impacts in a real system. Features like the
system cache, the FMPLL and the flash access times tend to provide the most significant performance
impacts in terms of hardware settings.
The subsequent sections in this chapter will describe how to configure and use these features appropriately.
33.3
Configuring Hardware Features
33.3.1
Branch Target Buffer (BTB)
33.3.1.1
Description
To resolve branch instructions and improve the accuracy of branch predictions the e200z7 core implements
a dynamic branch prediction mechanism using a branch target buffer (BTB), a fully associative address
cache of branch target addresses. Its purpose is to accelerate the execution of software loops with some
potential change of flow within the loop body. In addition, the BTB on the e200z7 has a subroutine call
stack that speeds up indirect branches.
33.3.1.2
Recommended Configuration
By default, this BTB is disabled following negation of reset. It is controlled by the Branch Unit Control
and Status Register (BUCSR). The BTB’s contents should be flushed and invalidated by writing
BUCSR[BBFI]=1, and it may be enabled by subsequently writing BUCSR[BPEN]=1.
Additional control is available in BUCSR[BPRED] and BUCSR[BALLOC] to control whether forward or
backward branches (or both) are candidates for entry into the BTB, and thus for branch prediction. By
default the BUCSR[BPRED] and BUCSR[BALLOC] fields are set to 0b00, which enables forward and
backward branch prediction. It is recommended to not disable branch prediction although for extremely
fine tuning of a given application the optimum setting of BUCSR[BPRED] and BUCSR[BALLOC]
should be assessed.
Содержание PXR4030
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Страница 120: ...Signal Descriptions 3 54 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 158: ...Power Management Controller PMC 5 26 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 182: ...Frequency Modulated Phase Locked Loop FMPLL 6 24 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 278: ...System Integration Unit SIU 7 96 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 280: ...System Information Module PXR40 Microcontroller Reference Manual Rev 1 8 2 Freescale Semiconductor...
Страница 300: ...Boot Assist Module BAM 9 20 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 346: ...Interrupts and Interrupt Controller INTC 10 46 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 352: ...General Purpose Static RAM SRAM 11 6 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 432: ...Core e200z7 Overview PXR40 Microcontroller Reference Manual Rev 1 13 44 Freescale Semiconductor...
Страница 460: ...Peripheral Bridge PBRIDGE 15 16 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 478: ...Memory Protection Unit MPU 16 18 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 496: ...Error Correction Status Module ECSM 17 18 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 524: ...Periodic Interrupt Timer PIT_RTI 20 12 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 740: ...FlexRay Communication Controller FLEXRAY 22 156 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 860: ...FlexCAN Module 24 50 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 928: ...Deserial Serial Peripheral Interface DSPI 25 68 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 982: ...Enhanced Serial Communication Interface eSCI 26 54 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 1114: ...Enhanced Queued Analog to Digital Converter EQADC 27 132 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 1167: ...Decimation Filter Freescale Semiconductor 28 53 PXR40 Microcontroller Reference Manual Rev 1...
Страница 1168: ...Decimation Filter 28 54 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 1262: ...Enhanced Time Processing Unit eTPU2 29 94 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 1399: ...Nexus Development Interface NDI Freescale Semiconductor 31 83 PXR40 Microcontroller Reference Manual Rev 1...
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