[RFC 0/3] powerpc: memory copy routines tweaked for Cell

[Gunnar von Boehn]

Hi Arnd,

I have no results for P5/P6, but I did some tests on JS21 aka PPC-970.
On PPC-970 the CELL memcpy is faster than the current Linux routine.
This becomes really visible when you really copy memory-to-memory and are
not only working in the 2ndlevelcache.


Kind regards

Gunnar von Boehn




                                                                           
             Arnd Bergmann                                                 
             <arnd at arndb.de>                                               
                                                                        To 
             19/06/2008 13:53          linuxppc-dev at ozlabs.org             
                                                                        cc 
                                       Mark Nelson <markn at au1.ibm.com>,    
                                       cbe-oss-dev at ozlabs.org, Gunnar von  
                                       Boehn/Germany/Contr/IBM at IBMDE,      
                                       Michael Ellerman                    
                                       <ellerman at au1.ibm.com>              
                                                                   Subject 
                                       Re: [RFC 0/3] powerpc: memory copy  
                                       routines tweaked for Cell           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           




On Thursday 19 June 2008, Mark Nelson wrote:
> The plan is to use Michael Ellerman's code patching work so that at
runtime
> if we're running on a Cell machine the new routines are called but
otherwise
> the existing memory copy routines are used.

Have you tried running this code on other platforms to see if it
actually performs worse on any of them? I would guess that the
older code also doesn't work too well on Power 5 and Power 6, so the
cell optimized version could give us a significant advantage as well,
albeit less than another CPU specific version.

             Arnd <><