[ECOS] Re: Silly question about ARM thumb

[Grant Edwards]

> It is possible to see some improvement in performance with
> Thumb mode when the core does not have cache (fetching each
> instruction off the external memory) & the bus size is 16
> bits.

That sounds quite possible.  If you're being severely limited
by instruction memory bandwidth, the reduced bandwidth required
for thumb mode may outweigh the icnrease in the number of
instructions required to perform a given task in thumb mode.

If you're running from fast 32-bit memory or if you have a
decent i-cache, I would expect that thumb performance would be
worse, since the CPU has to execute upwards of 50% more
instructions than it would in 32-bit mode.

-- 
Grant Edwards
grante@visi.com

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