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author | Michael Cree <mcree@orcon.net.nz> | 2012-08-19 14:40:58 +1200 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-08-19 08:41:18 -0700 |
commit | f2db633d301b4b50f5f93de0e8314cc81e9bc7de (patch) | |
tree | aafa01b17e83221ca92ee58e66d7e6783808a224 /kernel | |
parent | d8d5da129857bfd54b603771fca5409062167392 (diff) | |
download | op-kernel-dev-f2db633d301b4b50f5f93de0e8314cc81e9bc7de.zip op-kernel-dev-f2db633d301b4b50f5f93de0e8314cc81e9bc7de.tar.gz |
alpha: Use new generic strncpy_from_user() and strnlen_user()
Similar to x86/sparc/powerpc implementations except:
1) we implement an extremely efficient has_zero()/find_zero()
sequence with both prep_zero_mask() and create_zero_mask()
no-operations.
2) Our output from prep_zero_mask() differs in that only the
lowest eight bits are used to represent the zero bytes
nevertheless it can be safely ORed with other similar masks
from prep_zero_mask() and forms input to create_zero_mask(),
the two fundamental properties prep_zero_mask() must satisfy.
Tests on EV67 and EV68 CPUs revealed that the generic code is
essentially as fast (to within 0.5% of CPU cycles) of the old
Alpha specific code for large quadword-aligned strings, despite
the 30% extra CPU instructions executed. In contrast, the
generic code for unaligned strings is substantially slower (by
more than a factor of 3) than the old Alpha specific code.
Signed-off-by: Michael Cree <mcree@orcon.net.nz>
Acked-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
0 files changed, 0 insertions, 0 deletions