selinux: de-crapify avc cache stat code generation

044aea9b · Linus Torvalds <[email protected]> · 2011-05-19 18:59:47 -07:00

You can turn off the avc cache stats, but distributions seem to not do
that (perhaps because several performance tuning how-to's talk about the
avc cache statistics).

Which is sad, because the code it generates is truly horrendous, with
the statistics update being sandwitched between get_cpu/put_cpu which in
turn causes preemption disables etc.  We're talking ten+ instructions
just to increment a per-cpu variable in some pretty hot code.

Fix the craziness by just using 'this_cpu_inc()' instead.  Suddenly we
only need a single 'inc' instruction to increment the statistics.  This
is quite noticeable in the incredibly hot avc_has_perm_noaudit()
function (which triggers all the statistics by virtue of doing an
avc_lookup() call).

Signed-off-by: Linus Torvalds <[email protected]>

Commit

044aea9b83614948c98564000db07d1d32b2d29b

Parents

39ab05c8

Changes

1 files changed · +1 −5