Commit c9f34013 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman

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

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: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210118123451.1452206-1-npiggin@gmail.com
parent 9dd31b11
...@@ -505,18 +505,14 @@ config HOTPLUG_CPU ...@@ -505,18 +505,14 @@ config HOTPLUG_CPU
Say N if you are unsure. Say N if you are unsure.
config PPC_QUEUED_SPINLOCKS config PPC_QUEUED_SPINLOCKS
bool "Queued spinlocks" bool "Queued spinlocks" if EXPERT
depends on SMP depends on SMP
default PPC_BOOK3S_64
help help
Say Y here to use queued spinlocks which give better scalability and Say Y here to use queued spinlocks which give better scalability and
fairness on large SMP and NUMA systems without harming single threaded fairness on large SMP and NUMA systems without harming single threaded
performance. 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 config ARCH_CPU_PROBE_RELEASE
def_bool y def_bool y
depends on HOTPLUG_CPU depends on HOTPLUG_CPU
......
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