On 7/7/2017 7:44 AM, Binyamin Dissen wrote:
How big is the performance cost of running ARMODE?
Should there be a section of code that uses only ALET 0, is it best to go into
primary mode for that section?
Nothing, so long as AR translation is not required. And an ALET of 0
(or 1) would never require ART to be performed (as the hardware
understands it is a special ALET value).
There is actually a significant CPU cost to switch between primary and
AR mode using SAC, and slightly less (but still significant) for SACF.
If this was frequently executed, performance sensitive, code I would
recommend staying in a mode for as long as possible. Of course if you
are in AR mode and need to call a service that requires you to be in
primary mode then you must accept the cost and switch modes.
Regards,
Greg
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