[linuxsh-shmedia-dev] Optimizations and bug fixes to the SHmedia Linux kernel...

[Gaster, B. <ben...@su...>]

Hello!

I am planning to update the external bk repository for SHmedia Linux
later today to include work that we have been doing over the last month.
This work is best split into two categories:

 1. Optimizations=20
 2. Bug fixes

The work on optimizations includes enabling PCI DMA transfers which
itself required fixing a large number of bugs in the DMA code that was
disabled---I suppose this was why! Other optimizations that have been
done include:

   Optimized TLB miss handler
   Optimized flush_tlb_range
   Optimized PCI use of flush_cache_all
   Unnecessary 1ms delay when accessing device locations!

We are currently using versions of the SHmedia development tools, driven
by shared libraries, that in combination with the optimizations exposed
a number of bugs in SHmedia assembler inserts, in particular annotations
of insert arguments. We have began work on optimizing string.h for
SHmedia but there is still much work to be done here, in particular the
use of cache line allocation and prefetch.

Please read the change logs for a detailed description of the changes
included in today's push into the SHmedia Linux bk repository.=20

The great thing about these optimizations and bug fixes is that we now
have a SHmedia Linux kernel that is beginning to show responsiveness
similar to that of x86 Linux... WOW! There is still some way to go and
may more optimizations that can be done, reducing the TLB handler from 3
levels to 2 levels, thus avoiding an extra level of indirection, is just
one straight forward example.

We now have a kernel with video, sound, PCI USB, and webcam all running
for hours with "real time" performance! This is really excellent!

Cheers,

Ben.

Benedict R. Gaster
SuperH
2430 Aztec West, Almondsbury, Bristol BS32 4AQ, UK