Heiko Carstens 4423028203 s390/spinlock: optimize spin_unlock code ... Use a memory barrier + store sequence instead of a load + compare and swap sequence to unlock a spinlock and an rw lock. For the spinlock case this saves us two memory reads and a not needed cpu serialization after the compare and swap instruction stored the new value. The kernel size (performance_defconfig) gets reduced by ~14k. Average execution time of a tight inlined spin_unlock loop drops from 5.8ns to 0.7ns on a zEC12 machine. An artificial stress test case where several counters are protected with a single spinlock and which are only incremented while holding the spinlock shows ~30% improvement on a 4 cpu machine. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>		2014-09-09 08:53:30 +02:00
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asm	s390/spinlock: optimize spin_unlock code	2014-09-09 08:53:30 +02:00
uapi/asm	s390: wire up memfd_create syscall	2014-08-12 13:00:08 +02:00