x86, pvticketlock: When paravirtualizing ticket locks, increment by 2

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Increment ticket head/tails by 2 rather than 1 to leave the LSB free
to store a "is in slowpath state" bit.  This halves the number
of possible CPUs for a given ticket size, but this shouldn't matter
in practice - kernels built for 32k+ CPU systems are probably
specially built for the hardware rather than a generic distro
kernel.

Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Link: http://lkml.kernel.org/r/1376058122-8248-9-git-send-email-raghavendra.kt@linux.vnet.ibm.com
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: Attilio Rao <attilio.rao@citrix.com>
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

...

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Jeremy Fitzhardinge 2013-08-09 19:51:56 +05:30 • committed by H. Peter Anvin

parent 354714dd26

commit 4a1ed4ca68

2 changed files with 14 additions and 6 deletions

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10

arch/x86/include/asm/spinlock.h

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10

arch/x86/include/asm/spinlock_types.h

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