L2cache

Title:

    L2cache

Description:

    A little utility to increase performance on your Sam460ex and Sam460cr board

What it does:

    * on the 460ex CPU, coherency between memory and L2 cache can be managed via

      hardware snoop mechanism.
      Under some circumstances, the L2 controller may miss snoop-able write
requestes 
      and cause incoherency between L2 cache and main memory.

      To avoid this potential problem, the AOS4.1 kernel on Sam460 disable L2
cache 
      write by default, slightly degrading performance.

      This utility enables L2 cache write and thus increases a little system
performance.
      
      To be noted: IT MAY CAUSE SYSTEM INSTABILITY AND/OR DATA CORRUPTION if for

      some reason the OS perfom some operation which can cause incoherency
between 
      L2 cache and main memory, use it at your own risk !

      Once L2 cache write is enabled, Ragemem will report around 35% speed
increase 
      in the L2 WRITE32/WRITE64 test, and some application may see improved
performance
      too (for example 3-5% speed increase in MPlayer with some videos)

      The best use of this utility is to run it before any intensive task (for
example 
      playing a movie) then disable it, and not leaving it enabled all the time,
to 
      avoid any potential coherency problem.

How to use:

    * if run from the shell without any argument, enables L2 cache write.
      It accept the following arguments:
         VERBOSE to show some informations
         OFF to disable L2 cache write and resume normal operations
        
Notes:

    * the new setting doesn't survive a machine or OS reset.

History:

06-Dic-2014 - Version 1.0
      first release.