| Message ID | 20201221032226.888758-1-npiggin@gmail.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | powerpc: always enable queued spinlocks for 64s, disable for others | expand |
Le 21/12/2020 à 04:22, Nicholas Piggin a écrit : > 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> > --- > arch/powerpc/Kconfig | 8 +++----- > 1 file changed, 3 insertions(+), 5 deletions(-) > > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > index ae7391627054..1f9f9e64d638 100644 > --- a/arch/powerpc/Kconfig > +++ b/arch/powerpc/Kconfig > @@ -255,6 +255,7 @@ config PPC > select PCI_MSI_ARCH_FALLBACKS if PCI_MSI > select PCI_SYSCALL if PCI > select PPC_DAWR if PPC64 > + select PPC_QUEUED_SPINLOCKS if !EXPERT && PPC_BOOK3S_64 && SMP The condition is a bit complicated, and it doesn't set it to Y by default when EXPERT is selected. > select RTC_LIB > select SPARSE_IRQ > select SYSCTL_EXCEPTION_TRACE > @@ -506,16 +507,13 @@ config HOTPLUG_CPU > config PPC_QUEUED_SPINLOCKS > bool "Queued spinlocks" > depends on SMP > + depends on EXPERT || PPC_BOOK3S_64 > + I would do: config PPC_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 > Christophe
Excerpts from Christophe Leroy's message of December 21, 2020 4:04 pm: > > > Le 21/12/2020 à 04:22, Nicholas Piggin a écrit : >> 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> >> --- >> arch/powerpc/Kconfig | 8 +++----- >> 1 file changed, 3 insertions(+), 5 deletions(-) >> >> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig >> index ae7391627054..1f9f9e64d638 100644 >> --- a/arch/powerpc/Kconfig >> +++ b/arch/powerpc/Kconfig >> @@ -255,6 +255,7 @@ config PPC >> select PCI_MSI_ARCH_FALLBACKS if PCI_MSI >> select PCI_SYSCALL if PCI >> select PPC_DAWR if PPC64 >> + select PPC_QUEUED_SPINLOCKS if !EXPERT && PPC_BOOK3S_64 && SMP > > The condition is a bit complicated, and it doesn't set it to Y by default when EXPERT is selected. Yeah, I don't know how to do that (switch people's oldconfig from =N to =Y) otherwise (without renaming the option). I think it's enough though, experts should have said yes already :) > >> select RTC_LIB >> select SPARSE_IRQ >> select SYSCTL_EXCEPTION_TRACE >> @@ -506,16 +507,13 @@ config HOTPLUG_CPU >> config PPC_QUEUED_SPINLOCKS >> bool "Queued spinlocks" >> depends on SMP >> + depends on EXPERT || PPC_BOOK3S_64 >> + > > I would do: > > config PPC_QUEUED_SPINLOCKS > bool "Queued spinlocks" if EXPERT > depends on SMP > default PPC_BOOK3S_64 That's nicer. Thanks, Nick
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index ae7391627054..1f9f9e64d638 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -255,6 +255,7 @@ config PPC select PCI_MSI_ARCH_FALLBACKS if PCI_MSI select PCI_SYSCALL if PCI select PPC_DAWR if PPC64 + select PPC_QUEUED_SPINLOCKS if !EXPERT && PPC_BOOK3S_64 && SMP select RTC_LIB select SPARSE_IRQ select SYSCTL_EXCEPTION_TRACE @@ -506,16 +507,13 @@ config HOTPLUG_CPU config PPC_QUEUED_SPINLOCKS bool "Queued spinlocks" depends on SMP + depends on EXPERT || 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
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> --- arch/powerpc/Kconfig | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-)