In powerpc32 architecture there is a function called cacheable_memcpy()
which does same thing as memcpy() but using dcbz/dcbt instructions for
an optimised copy (just like __copy_tofrom_user())
What seems strange is that it is almost nowhere used (only used in
drivers/net/ethernet/ibm/emac/core.c)
For a try I replaced all memcpy() in include/linux/skbuff.h and
net/core/skbuff.c by cacheable_memcpy() and I got around 8% improvement
on FTP throughput on MPC885.
What could be done to generalise the use of cacheable_memcpy() instead
of memcpy() whenever possible ?
Indeed, in order to use cacheable_memcpy(), we need
* The destination to be cacheable
* The source and destination to not overlap on the same cachelines
Could we check, when calling memcpy(), whether the destination is
cacheable or not, and if yes redirect the call to cacheable_memcpy() ?
How can we check that ?
Christophe
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