diff options
author | Mateusz Guzik <mjg@FreeBSD.org> | 2017-02-05 08:04:11 +0000 |
---|---|---|
committer | Mateusz Guzik <mjg@FreeBSD.org> | 2017-02-05 08:04:11 +0000 |
commit | 08da2677755f0874ea99c5a42181aacc3eb17690 (patch) | |
tree | d6b4cc3e07b0115a5d319049fb2d06f403f462c7 /sys/sys/mtio.h | |
parent | 3ae56ce958972a69123031d7bfab3d7243ec9189 (diff) | |
download | src-08da2677755f0874ea99c5a42181aacc3eb17690.tar.gz src-08da2677755f0874ea99c5a42181aacc3eb17690.zip |
mtx: move lockstat handling out of inline primitives
Lockstat requires checking if it is enabled and if so, calling a 6 argument
function. Further, determining whether to call it on unlock requires
pre-reading the lock value.
This is problematic in at least 3 ways:
- more branches in the hot path than necessary
- additional cacheline ping pong under contention
- bigger code
Instead, check first if lockstat handling is necessary and if so, just fall
back to regular locking routines. For this purpose a new macro is introduced
(LOCKSTAT_PROFILE_ENABLED).
LOCK_PROFILING uninlines all primitives. Fold in the current inline lock
variant into the _mtx_lock_flags to retain the support. With this change
the inline variants are not used when LOCK_PROFILING is defined and thus
can ignore its existence.
This results in:
text data bss dec hex filename
22259667 1303208 4994976 28557851 1b3c21b kernel.orig
21797315 1303208 4994976 28095499 1acb40b kernel.patched
i.e. about 3% reduction in text size.
A remaining action is to remove spurious arguments for internal kernel
consumers.
Notes
Notes:
svn path=/head/; revision=313275
Diffstat (limited to 'sys/sys/mtio.h')
0 files changed, 0 insertions, 0 deletions