We are running a survey to help us improve the experience for all of our members. If you see the survey appear, please take the time to tell us about your experience if you can.
Hello,
I am working with ARMV8 Cortex A72 architecture,i want to know can i turn off branch prediction?and how can i do it?
best regards,
I guess it can't (ARM 100095_0003_06_en):6.5.5 Enabling program flow prediction Program flow prediction is always enabled and no programming is required to take advantage ofprogram flow prediction.When reset, the processor:• Invalidates the BTB.• Resets the GHB and indirect predictor to a known state.No software intervention is required to prepare the prediction logic before enabling program flowprediction.
Hi Rifakst,
The CPU Auxiliary Control Register (CPUACTLR_EL1) of the Cortex-A72 provides some level of control over the branch prediction:
Bit 34 disables static branch predictor.
Bit 33 disables main prediction suppression at target fetch of microBTB.
Bit 4 disables indirect predictor.
Bit 3 disables micro BTB.
The section Program flow prediction of A72 TRM gives some details about each function.
Best regards,
Vincent.