Re: Optimised memset64/memset32 for powerpc

["Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>]

On 2017/03/22 12:30PM, Matthew Wilcox wrote:
> On Wed, Mar 22, 2017 at 06:18:05AM -0700, Matthew Wilcox wrote:
> > There's one other potential user I've been wondering about, which are the
> > various console drivers.  They use 'memsetw' to blank the entire console
> > or lines of the console when scrolling, but the only architecture which
> > ever bothered implementing an optimised version of it was Alpha.
> > 
> > Might be worth it on powerpc actually ... better than a loop calling
> > cpu_to_le16() on each iteration.  That'd complete the set with a
> > memset16().
> 
> All hail plane rides ... This would need to be resplit and merged properly,
> but I think it makes life a little saner.

... not to forget train rides :)

Here's a straight-forward implementation for powerpc64, along with one
other user in bpf. It is obviously non-critical, but given that we have
64K pages on powerpc64, it does help to speed up the BPF JIT.

- Naveen

Naveen N. Rao (2):
  powerpc: string: implement optimized memset variants
  powerpc: bpf: use memset32() to pre-fill traps in BPF page(s)

 arch/powerpc/include/asm/string.h | 24 ++++++++++++++++++++++++
 arch/powerpc/lib/mem_64.S         | 19 ++++++++++++++++++-
 arch/powerpc/net/bpf_jit_comp64.c |  6 +-----
 3 files changed, 43 insertions(+), 6 deletions(-)

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2.11.1