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| author |   Linus Torvalds <torvalds@linux-foundation.org> | 2013-12-27 15:30:58 -0800 |
|---|---|---|
| committer |   H. Peter Anvin <hpa@zytor.com> | 2013-12-27 16:58:17 -0800 |
| commit | c5fe5d80680e2949ffe102180f5fc6cefc0d145f (patch) | |
| tree | ca8b287deb7c2fc0167e31dd08de2f5397a33728 /tools/perf/scripts/python/export-to-postgresql.py | |
| parent | x86-64, copy_user: Use leal to produce 32-bit results (diff) | |
| download | linux-dev-c5fe5d80680e2949ffe102180f5fc6cefc0d145f.tar.xz linux-dev-c5fe5d80680e2949ffe102180f5fc6cefc0d145f.zip | |
x86: Replace assembly access_ok() with a C variant
It turns out that the assembly variant doesn't actually produce that
good code, presumably partly because it creates a long dependency
chain with no scheduling, and partly because we cannot get a flags
result out of gcc (which could be fixed with asm goto, but it turns
out not to be worth it.)
The C code allows gcc to schedule and generate multiple (easily
predictable) branches, and as a side benefit we can really optimize
the case where the size is constant.
Link: http://lkml.kernel.org/r/CA%2B55aFzPBdbfKovMT8Edr4SmE2_=%2BOKJFac9XW2awegogTkVTA@mail.gmail.com
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'tools/perf/scripts/python/export-to-postgresql.py')
0 files changed, 0 insertions, 0 deletions