Hi folks,

Any comment on this is appreciated.

Thanks, Yang

On 12/9/2015 2:43 PM, Yang Shi wrote:

The functionality of context tracking has been implemented by PPC64 and HAVE_CONTEXT_TRACKING was selected by pseries by default. Actually, it is applicale to all PPC64 platforms, so select it in PPC64 generic Kconfig.

NO_HZ_FULL depends on it, with this change NO_HZ_FULL could be enabled for all PPC64 machines.

Signed-off-by: Yang Shi yang.shi@linaro.org

Following the instruction in Documentation/timers/NO_HZ.txt, I tested full nohz on my FSL T2080 target, the below trace log shows it works well.

    user_loop-574   [001] d..1   137.044892: tick_stop: success=yes msg=
    user_loop-574   [001] d.h1   138.044880: hrtimer_expire_entry: hrtimer=c00000007fd22d10 function=.tick_sched_timer now=137796002092
    user_loop-574   [001] d.h1   139.044880: hrtimer_expire_entry: hrtimer=c00000007fd22d10 function=.tick_sched_timer now=138796002129
    user_loop-574   [001] d.h1   140.044880: hrtimer_expire_entry: hrtimer=c00000007fd22d10 function=.tick_sched_timer now=139796002219
    user_loop-574   [001] d.h1   141.044880: hrtimer_expire_entry: hrtimer=c00000007fd22d10 function=.tick_sched_timer now=140796002229
    user_loop-574   [001] d.h1   142.044879: hrtimer_expire_entry: hrtimer=c00000007fd22d10 function=.tick_sched_timer now=141796002159
    user_loop-574   [001] d.h1   143.044879: hrtimer_expire_entry: hrtimer=c00000007fd22d10 function=.tick_sched_timer now=142796002142
    user_loop-574   [001] d.h1   144.044878: hrtimer_expire_entry: hrtimer=c00000007fd22d10 function=.tick_sched_timer now=143796002046
    user_loop-574   [001] d.h1   145.044878: hrtimer_expire_entry: hrtimer=c00000007fd22d10 function=.tick_sched_timer now=144796002189
    user_loop-574   [001] d.h1   146.044878: hrtimer_expire_entry: hrtimer=c00000007fd22d10 function=.tick_sched_timer now=145796002199
    user_loop-574   [001] d.h1   147.044880: hrtimer_expire_entry: hrtimer=c00000007fd22d10 function=.tick_sched_timer now=146796003836

It shows the timer tick just comes in every second.

It should be low risk to have problem on other PPC64 targets, although they are not tested.

arch/powerpc/platforms/Kconfig.cputype | 1 + arch/powerpc/platforms/pseries/Kconfig | 1 - 2 files changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype index 142dff5..7b25dd1 100644 --- a/arch/powerpc/platforms/Kconfig.cputype +++ b/arch/powerpc/platforms/Kconfig.cputype @@ -3,6 +3,7 @@ config PPC64 default n select HAVE_VIRT_CPU_ACCOUNTING select ZLIB_DEFLATE

• select HAVE_CONTEXT_TRACKING help This option selects whether a 32-bit or a 64-bit kernel will be built.

diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig index bec90fb..6853148 100644 --- a/arch/powerpc/platforms/pseries/Kconfig +++ b/arch/powerpc/platforms/pseries/Kconfig @@ -17,7 +17,6 @@ config PPC_PSERIES select PPC_UDBG_16550 select PPC_NATIVE select PPC_DOORBELL

• select HAVE_CONTEXT_TRACKING select HOTPLUG_CPU if SMP select ARCH_RANDOM select PPC_DOORBELL