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It's a truism that if an application dataset is larger or differently organised than the limits/constraints of the Parallella architecure then that application will need to work around/within the constraints, such as the 8KB segmentation mentioned.
It's probably a only small subset of applications/developers that really need to access large contiguous datasets in the current Parallella's global memory - so not a big issue.
For those who do need it, perhaps it would be best to just document how to adjust the size and location of the global memory more flexibly/easilly - especially for a E64 build, say, -rather than have it fixed at 32MB. { ... like one of shodruck's Ubunu tips maybe?}
But having access to a large global memory and then actually using it is not straightforward.
The performance hit of accessing the off-chip memory is itself a major constraint - and many developers will have to take this into account even for basic applications.
There's a good analysis/advice by @tnt on the performance impact of reading data/running code from the external global memory on one of the early boards.
.
Basically - don't. Unless you must.
tery
Statistics: Posted by greytery — Mon Apr 14, 2014 11:07 am
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In any case, with Epiphany, we have to manage data segmented into 8KB or so.
Statistics: Posted by shodruk — Sun Apr 13, 2014 4:31 pm
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Question for all: How big of an issue is it to not support large contiguous areas of physical memory for software developers? Our assumption was that that this could be hidden from most users.
Andreas
Statistics: Posted by aolofsson — Sun Apr 13, 2014 1:38 pm
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the Core-ID of Epiphany is set to (32-35, 8-11),
so the Epiphany can only access its east address (0-63, 12-63).
e.g.
0x00c00000 - 0x03ffffff
0x04c00000 - 0x07ffffff
0x08c00000 - 0x0bffffff
...
0xfcc00000 - 0xffffffff
So we can get up to 52MB contiguous memory space. (with E16 Parallella)
Note: This is only my understanding...
Statistics: Posted by shodruk — Sun Apr 13, 2014 12:42 pm
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@timpart - that's a very polite RTFM. Thankyou.
Got a bit carried away there.
Ho Hum, back to the manual until I get the real thing to play with.
tery
Statistics: Posted by greytery — Sun Apr 13, 2014 8:52 am
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