[fpc-devel] Patch, font rendering on Arm-Linux devices.

[Daniël Mantione]

Op Fri, 29 Feb 2008, schreef Christian Iversen:

>> Instead "unaligned" will simulate an unaligned load with two loads and some 
>> rotation etc. On the ARM, where every mnemonic can rotate operands, this is 
>> isn't that bad of a penalty.
>> 
>> Therefore, I wouldn't be surprised that even on ARM, arrays with packed 
>> structures are faster than arrays with unpacked structures.
>
> That's possible. Why would it be faster, btw? Better cache coherency?

Like I mentioned, unliek modern x86 processors, ARM processors cannot 
detect an array traversal and preload the array into the cache. If the 
array is not in cache, you get cache miss after cache miss.

A cache miss is very expensive with latencies of modern memory. A smaller 
array results in less cache misses.

Daniël