Efficient memcpy()/memmove() for G2/G3 cores...

Steven Munroe munroesj at linux.vnet.ibm.com
Sat Aug 30 06:34:21 EST 2008


On Fri, 2008-08-29 at 13:48 +0200, David Jander wrote:
> On Wednesday 27 August 2008 23:04:39 Steven Munroe wrote:
> > On Tue, 2008-08-26 at 08:28 +1000, Benjamin Herrenschmidt wrote:
> > > On Mon, 2008-08-25 at 15:06 +0200, David Jander wrote:
> > > > Hi Matt,
> > > >
> > > > On Monday 25 August 2008 13:00:10 Matt Sealey wrote:
> > > > > The focus has definitely been on VMX but that's not to say lower
> > > > > power processors were forgotten :)
> > > >
[SNIP]
> > >
> > > It would be useful of somebody interested in getting things things
> > > into glibc did the necessary FSF copyright assignment stuff and worked
> > > toward integrating them.
> >
> > Ben makes a very good point!
> 
> Sounds reasonable... but I am still wondering about what you mean 
> with "things"?
> AFAICS there is almost nothing there (besides the memcpy() routine from Gunnar 
> von Boehn, which is apparently still far from optimal). And I was asking for 
> someone to correct me here ;-)
> 
> > There is also a framework for adding and maintaining optimizations of
> > this type:
> > 
> > http://penguinppc.org/dev/glibc/glibc-powerpc-cpu-addon.html
> 
> I had already stumbled across this one, but it seems to focus on G3 or newer 
> processors (power4). There is no optimal memcpy() for G2/PPC603/e300.
> 
Well folks volunteer to work on code for the hardware they have, use,
and care about. I don't have any of that hardware...

this framework can be used to add optimizations for any valid gcc
-mcpu=<cpu-type> target.

> >[...]
> > So it does no good to complain here. If you have core you want to
> > contribute, Get your FSF CR assignment and join #glibc on freenode IRC.
> 
> I am not complaining. I was only wondering if it is just me or there really is 
> very little that has been done (for either uClibc, glibc, or whatever for 
> powerpc) to improve performance of (linux-) applications on "lower"-power 
> platforms (G2 core), AFAICS there is a LOT that can be gained by simple 
> tweaks.
> 
This is a self help group (free as in freedom) We help each other. And
you can help yourself. There is no free lunch.

> > And we will help you.
[SNIP]
> 
> The problem is: I have very little experience with powerpc assembly and only 
> very limited time to dedicate to this and I am looking for others who have 
> 
Well this will be a good learning experience for you. We will try to
answer questions.





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