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powerpc: Always enable queued spinlocks for 64s, disable for others

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Queued spinlocks have shown to have good performance and fairness
properties even on smaller (2 socket) POWER systems. This selects them
automatically for 64s. For other platforms they are de-selected, the
standard spinlock is far simpler and smaller code, and single chips
with a handful of cores is unlikely to show any improvement.

CONFIG_EXPERT still allows this to be changed, e.g., to help debug
performance or correctness issues.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210118123451.1452206-1-npiggin@gmail.com
This commit is contained in:
Nicholas Piggin 2021-01-18 22:34:51 +10:00 committed by Michael Ellerman
parent 9dd31b1137
commit c9f3401313
1 changed files with 2 additions and 6 deletions
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8
arch/powerpc/Kconfig
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@ -505,18 +505,14 @@ config HOTPLUG_CPU
Say N if you are unsure.
config PPC_QUEUED_SPINLOCKS
bool "Queued spinlocks"
bool "Queued spinlocks" if EXPERT
depends on SMP
default PPC_BOOK3S_64
help
Say Y here to use queued spinlocks which give better scalability and
fairness on large SMP and NUMA systems without harming single threaded
performance.
This option is currently experimental, the code is more complex and
less tested so it defaults to "N" for the moment.
If unsure, say "N".
config ARCH_CPU_PROBE_RELEASE
def_bool y
depends on HOTPLUG_CPU