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Altera_Forum
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13 years ago

Cache Behavior on NIOS-II

Hi everybody, I'm working on a project that needs me to fully understand how many cycles does d-cache/ i-cache needs to fetch the whole cache line. Assuming that the cache line size is 32b...
Altera_Forum's avatar
Altera_Forum
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13 years ago

Thank you for your explanation. However, I still have some questions.

When I did some experiments on the assembly level, I got some strange numbers.

When I read from an address that is already in the d-cache it takes one clock cycle. On the other hand, when I read from an address that is not in the d-cache it takes much more than one extra cycle to access the on-chip memory on avalon-bus. Even when I instruct the Qsys not to add any register in between to improve fmax, the result still a does not make any sense.

So my question will be how many cycles the CPU takes to read from on-chip memory that is connected through Avalon-bus.

1. using normal asm(ldw)

2. using IO asm(ldwio)

Thank you again for your support.