[PATCH v2 0/6] powerpc32: replace memcpy and memset by cacheable alternatives

David Laight David.Laight at ACULAB.COM
Tue May 19 21:43:13 AEST 2015

From: Christophe Leroy
> Sent: 19 May 2015 11:08
> This patchset implements use of cacheable versions of memset and
> memcpy since when the destination is not cacheable, memset_io
> and memcpy_toio are used.

This isn't the right list to ask, but:

Can someone fix the x86 versions of memset/memcpy (and the _io variants)
so that they don't end up being 'rep movsb' on new intel cpus?

I've a C2558 Atom which has the optimised 'rep movsb' hardware.
Copies to/from uncached locations are now done 'byte by byte'.
As well as kernel code this affects userpace copying to/from
mmap()ed PCIe space.
64bit reads are slow enough, making it 8 times slower is horrid.

I suspect this affect some network drivers as well.


More information about the Linuxppc-dev mailing list