[cpuops cmpxchg double V3 0/5] this_cpu_cmpxchg_double support
From: Christoph Lameter
Date: Fri Feb 25 2011 - 12:42:00 EST
This patch series introduces this_cpu_cmpxchg_double().
x86 cpus support cmpxchg16b and cmpxchg8b instuction which are capable of
switching two words instead of one during a cmpxchg.
Two words allow to swap more state in an atomic instruction.
this_cpu_cmpxchg_double() is used in the slub allocator to avoid
interrupt disable/enable in both alloc and free fastpath.
Using the new operation significantly speeds up the fastpaths.
- Change parameter convention for this_cpu_cmpxchg_double. Specify both
percpu variables in same way as the two old and new values.
- Do not require a per cpu pointer but a variable to conform to the
convention used in other this_cpu_ops.
- Do not use CONFIG_DEBUG_VM to enable cmpxchg diagnostics. Use
custom SLUB define instead.
- Add patch to move min_partial into a different cacheline.
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