| Message ID | 20230818050739.827851-1-vaibhav@linux.ibm.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 0ceef6e99cc3a57f33b84dafc6df5dfb3b28278d |
| Headers | show |
| Series | powerpc: Enable generic cpu idle-loop | expand |
Vaibhav Jain <vaibhav@linux.ibm.com> writes: > This minor patch enables config option GENERIC_IDLE_POLL_SETUP for arch > powerpc. This should add support for kernel param 'nohlt'. Which is named after an 8086 instruction :), but oh well. > Powerpc kernel also supports another kernel boot-time param called > 'powersave' which can also be used to disable all cpu idle-states and > forces CPU to an idle-loop similar to what cpu_idle_poll() does. This > patch however makes powerpc kernel-parameters better aligned to the > generic boot-time parameters. It would be nice if we could make our powersave=off parameter just enable this generic logic. Have you looked at if that's possible? At a glance it looks like it should be, when cpu_idle_force_poll is true do_idle() never calls cpuidle_idle_call(), so the cpuidle drivers are never invoked. cheers
Thanks for looking at this patch Mpe. Michael Ellerman <mpe@ellerman.id.au> writes: > Vaibhav Jain <vaibhav@linux.ibm.com> writes: >> This minor patch enables config option GENERIC_IDLE_POLL_SETUP for arch >> powerpc. This should add support for kernel param 'nohlt'. > > Which is named after an 8086 instruction :), but oh well. > Thanks. This is an interesting trivia :) >> Powerpc kernel also supports another kernel boot-time param called >> 'powersave' which can also be used to disable all cpu idle-states and >> forces CPU to an idle-loop similar to what cpu_idle_poll() does. This >> patch however makes powerpc kernel-parameters better aligned to the >> generic boot-time parameters. > > It would be nice if we could make our powersave=off parameter just > enable this generic logic. > > Have you looked at if that's possible? At a glance it looks like it > should be, when cpu_idle_force_poll is true do_idle() never calls > cpuidle_idle_call(), so the cpuidle drivers are never invoked. Thanks for suggesting this and it looks like a simple fix to arch/idle.c code. I have posted a v2 with the needed change on the mailing list at https://lore.kernel.org/all/20230821045928.1350893-1-vaibhav@linux.ibm.com
On Fri, 18 Aug 2023 10:37:37 +0530, Vaibhav Jain wrote: > This minor patch enables config option GENERIC_IDLE_POLL_SETUP for arch > powerpc. This should add support for kernel param 'nohlt'. > > Powerpc kernel also supports another kernel boot-time param called > 'powersave' which can also be used to disable all cpu idle-states and > forces CPU to an idle-loop similar to what cpu_idle_poll() does. This > patch however makes powerpc kernel-parameters better aligned to the > generic boot-time parameters. > > [...] Applied to powerpc/next. [1/1] powerpc: Enable generic cpu idle-loop https://git.kernel.org/powerpc/c/0ceef6e99cc3a57f33b84dafc6df5dfb3b28278d cheers
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 722b6eca2e93..6b657ebafcfb 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3738,7 +3738,7 @@ nohibernate [HIBERNATION] Disable hibernation and resume. - nohlt [ARM,ARM64,MICROBLAZE,MIPS,SH] Forces the kernel to + nohlt [ARM,ARM64,MICROBLAZE,MIPS,PPC,SH] Forces the kernel to busy wait in do_idle() and not use the arch_cpu_idle() implementation; requires CONFIG_GENERIC_IDLE_POLL_SETUP to be effective. This is useful on platforms where the diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 0b1172cbeccb..574661403800 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -193,6 +193,7 @@ config PPC select GENERIC_CPU_VULNERABILITIES if PPC_BARRIER_NOSPEC select GENERIC_EARLY_IOREMAP select GENERIC_GETTIMEOFDAY + select GENERIC_IDLE_POLL_SETUP select GENERIC_IRQ_SHOW select GENERIC_IRQ_SHOW_LEVEL select GENERIC_PCI_IOMAP if PCI
This minor patch enables config option GENERIC_IDLE_POLL_SETUP for arch powerpc. This should add support for kernel param 'nohlt'. Powerpc kernel also supports another kernel boot-time param called 'powersave' which can also be used to disable all cpu idle-states and forces CPU to an idle-loop similar to what cpu_idle_poll() does. This patch however makes powerpc kernel-parameters better aligned to the generic boot-time parameters. Signed-off-by: Vaibhav Jain<vaibhav@linux.ibm.com> --- Documentation/admin-guide/kernel-parameters.txt | 2 +- arch/powerpc/Kconfig | 1 + 2 files changed, 2 insertions(+), 1 deletion(-)