diff options
| author | Michael Ellerman <mpe@ellerman.id.au> | 2017-04-05 12:44:50 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-04-13 23:37:17 +1000 |
| commit | 40e275653e2cdb5be5aa828d31cc96eb0eef3346 (patch) | |
| tree | 9f981f00ae7d9c0cc9b812de09b50cf3b3999880 /arch/powerpc | |
| parent | ebbe9d7d3a2ca0d62f1a2c08c7e7a3e0a88cf999 (diff) | |
powerpc/powernv: Always enable SMP when building powernv
The powernv platform supports Power7 and later CPUs, all of which are
multithreaded and multicore.
As such we never build a SMP=n kernel for those machines, other than
possibly for debugging or running in a simulator.
In the debugging case we can get a similar effect by booting with
nr_cpus=1, or there's always the option of building a custom kernel with
SMP hacked out.
For running in simulators the code size reduction from building without
SMP is not particularly important, what matters is the number of
instructions executed. A quick test shows that a SMP=y kernel takes ~6%
more instructions to boot to a shell. Booting with nr_cpus=1 recovers
about half that deficit.
On the flip side, keeping the SMP=n kernel building can be a pain at
times. And although we've mostly kept it building in recent years, no
one is regularly testing that the SMP=n kernel actually boots and works
well on these machines.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/platforms/powernv/Kconfig | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/powernv/Kconfig b/arch/powerpc/platforms/powernv/Kconfig index 2489805e79f1..6a6f4ef46b9e 100644 --- a/arch/powerpc/platforms/powernv/Kconfig +++ b/arch/powerpc/platforms/powernv/Kconfig @@ -21,6 +21,7 @@ config PPC_POWERNV select CPU_FREQ_GOV_CONSERVATIVE select PPC_DOORBELL select MMU_NOTIFIER + select FORCE_SMP default y config OPAL_PRD |