a8ddac7e53
- atomic operations which both modify the variable and return something imply full smp memory barriers before and after the memory operations involved (failing atomic_cmpxchg, atomic_add_unless, etc don't imply a barrier because they don't modify the target). See Documentation/atomic_ops.txt. So remove extra barriers and branches. - All architectures support atomic_cmpxchg. This has no relation to __HAVE_ARCH_CMPXCHG. We can just take the atomic_cmpxchg path unconditionally This reduces a simple single threaded fastpath lock+unlock test from 590 cycles to 203 cycles on a ppc970 system. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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| .. | ||
| bitops | ||
| 4level-fixup.h | ||
| Kbuild | ||
| Kbuild.asm | ||
| atomic.h | ||
| audit_change_attr.h | ||
| audit_dir_write.h | ||
| audit_read.h | ||
| audit_signal.h | ||
| audit_write.h | ||
| bitops.h | ||
| bug.h | ||
| cmpxchg-local.h | ||
| cmpxchg.h | ||
| cputime.h | ||
| device.h | ||
| div64.h | ||
| dma-coherent.h | ||
| dma-mapping-broken.h | ||
| dma-mapping.h | ||
| emergency-restart.h | ||
| errno-base.h | ||
| errno.h | ||
| fcntl.h | ||
| futex.h | ||
| gpio.h | ||
| ide_iops.h | ||
| int-l64.h | ||
| int-ll64.h | ||
| ioctl.h | ||
| iomap.h | ||
| irq_regs.h | ||
| kdebug.h | ||
| libata-portmap.h | ||
| local.h | ||
| memory_model.h | ||
| mm_hooks.h | ||
| mman.h | ||
| mutex-dec.h | ||
| mutex-null.h | ||
| mutex-xchg.h | ||
| page.h | ||
| pci-dma-compat.h | ||
| pci.h | ||
| percpu.h | ||
| pgtable-nopmd.h | ||
| pgtable-nopud.h | ||
| pgtable.h | ||
| poll.h | ||
| resource.h | ||
| rtc.h | ||
| sections.h | ||
| siginfo.h | ||
| signal.h | ||
| statfs.h | ||
| syscall.h | ||
| termios.h | ||
| tlb.h | ||
| topology.h | ||
| uaccess.h | ||
| vmlinux.lds.h | ||
| xor.h | ||