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Mateusz Guzik 1ada904147 Implement trivial backoff for locking primitives.
All current spinning loops retry an atomic op the first chance they get,
which leads to performance degradation under load.

One classic solution to the problem consists of delaying the test to an
extent. This implementation has a trivial linear increment and a random
factor for each attempt.

For simplicity, this first thouch implementation only modifies spinning
loops where the lock owner is running. spin mutexes and thread lock were
not modified.

Current parameters are autotuned on boot based on mp_cpus.

Autotune factors are very conservative and are subject to change later.

Reviewed by:	kib, jhb
Tested by:	pho
MFC after:	1 week
2016-08-01 21:48:37 +00:00
bin sh: Fix a clang warning. 2016-07-31 13:11:34 +00:00
cddl Cast result from third parameter to int instead of promoting it to size_t 2016-07-31 06:03:27 +00:00
contrib Remove usage of _WITH_DPRINTF 2016-07-30 01:16:06 +00:00
crypto
etc
gnu
include Fix up setgrent(3) to have a POSIX-compliant prototype. 2016-07-31 08:05:15 +00:00
kerberos5
lib Fix up setgrent(3) to have a POSIX-compliant prototype. 2016-07-31 08:05:15 +00:00
libexec
release
rescue
sbin An old tables implementation had all tables preallocated, 2016-08-01 13:38:48 +00:00
secure
share Man page for the new checksum netgraph module. 2016-08-01 12:14:21 +00:00
sys Implement trivial backoff for locking primitives. 2016-08-01 21:48:37 +00:00
targets
tests
tools Remove calls to die added for associated bugs 2016-07-31 06:28:40 +00:00
usr.bin indent: Avoid using values of pointers that refer to deallocated space. 2016-08-01 19:24:01 +00:00
usr.sbin Fix non-functional bsdinstall services dialog. 2016-08-01 19:49:42 +00:00
.arcconfig
.arclint
COPYRIGHT
LOCKS
MAINTAINERS
Makefile
Makefile.inc1 Add libprocstat prebuild library dependencies. 2016-07-30 03:43:55 +00:00
Makefile.libcompat
ObsoleteFiles.inc
README
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