bae8f56734
In case a lock is contended it is better to do a load-and-test first before trying to get the lock with compare-and-swap. This helps to avoid unnecessary cache invalidations of the cacheline for the lock if the CPU has to wait for the lock. For an uncontended lock doing the compare-and-swap directly is a bit better, if the CPU does not have the cacheline in its cache yet the compare-and-swap will get it read-write immediately while a load-and-test would get it read-only first. Always to the load-and-test first to avoid the cacheline invalidations for the contended case outweight the potential read-only to read-write cacheline upgrade for the uncontended case. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> |
||
---|---|---|
.. | ||
appldata | ||
boot | ||
configs | ||
crypto | ||
hypfs | ||
include | ||
kernel | ||
kvm | ||
lib | ||
math-emu | ||
mm | ||
net | ||
oprofile | ||
pci | ||
defconfig | ||
Kbuild | ||
Kconfig | ||
Kconfig.debug | ||
Makefile |