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authorMateusz Guzik <mjg@FreeBSD.org>2017-02-05 08:04:11 +0000
committerMateusz Guzik <mjg@FreeBSD.org>2017-02-05 08:04:11 +0000
commit08da2677755f0874ea99c5a42181aacc3eb17690 (patch)
treed6b4cc3e07b0115a5d319049fb2d06f403f462c7 /sys/sys/mtio.h
parent3ae56ce958972a69123031d7bfab3d7243ec9189 (diff)
downloadsrc-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')
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