x in om2007.2

Carsten Haitzler (The Rasterman) raster at openmoko.org
Mon Jul 28 23:32:11 CEST 2008

On Sun, 27 Jul 2008 16:28:16 +0100 Andy Green <andy at openmoko.com> babbled:

> Hash: SHA1
> Somebody in the thread at some point said:
> |> Why is this so (lesser memory bandwidth due to the glamo chip)?
> |
> | because that is the nature of the hardware on the freerunner. the glamo
> | throttles write rates to its video ram (or read rates) and thus brings the
> | system into wait states waiting on the glamo (basically lock in your
> cpu down to
> | doing nothing WHILE you try and write data, and the writes do not go
> as fast
> | asht e cpu can manage - they hit about 7mb/sec - thats a fair bit less
> than
> | your average 100mbit ethernet can transport, and thats the video memory
> | access from the cpu). it's just that is how it is, and it is a limit
> you have to
> | code around - read/write less data to/from video ram on updates.
> Just a FYI, I have a pair of patches pending that claim to increase
> throughput to Glamo without introducing new instability, and it is
> possible to crank it up a bit more I think.

reducing waitstates? i remember olv hand to increase them to stop
instability... maybe it was a production issue at the time... any increase will
be very much welcomed - though i'd really like to see a 2x, 3x or 4x speedup or
more... but i doubt that's a happening thing. :(

Carsten Haitzler (The Rasterman) <raster at openmoko.org>

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