| Message ID | 20250102191856.499424-2-sshegde@linux.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | powerpc: Enable dynamic preemption | expand |
Hi Shrikanth, kernel test robot noticed the following build errors: [auto build test ERROR on powerpc/next] [cannot apply to powerpc/fixes linus/master v6.13-rc5 next-20241220] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch#_base_tree_information] url: https://github.com/intel-lab-lkp/linux/commits/Shrikanth-Hegde/powerpc-Enable-dynamic-preemption/20250103-032131 base: https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next patch link: https://lore.kernel.org/r/20250102191856.499424-2-sshegde%40linux.ibm.com patch subject: [PATCH v2 1/1] powerpc: Enable dynamic preemption config: powerpc-randconfig-r072-20250104 (https://download.01.org/0day-ci/archive/20250104/202501040657.5tSQad1Y-lkp@intel.com/config) compiler: clang version 20.0.0git (https://github.com/llvm/llvm-project 096551537b2a747a3387726ca618ceeb3950e9bc) reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250104/202501040657.5tSQad1Y-lkp@intel.com/reproduce) If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot <lkp@intel.com> | Closes: https://lore.kernel.org/oe-kbuild-all/202501040657.5tSQad1Y-lkp@intel.com/ All errors (new ones prefixed by >>): In file included from arch/powerpc/kernel/asm-offsets.c:12: In file included from include/linux/compat.h:14: In file included from include/linux/sem.h:5: In file included from include/uapi/linux/sem.h:5: In file included from include/linux/ipc.h:7: In file included from include/linux/rhashtable-types.h:12: In file included from include/linux/alloc_tag.h:11: In file included from include/linux/preempt.h:79: >> arch/powerpc/include/asm/preempt.h:8:1: error: type specifier missing, defaults to 'int'; ISO C99 and later do not support implicit int [-Wimplicit-int] 8 | DECLARE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched); | ^ | int >> arch/powerpc/include/asm/preempt.h:8:25: error: a parameter list without types is only allowed in a function definition 8 | DECLARE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched); | ^ In file included from arch/powerpc/kernel/asm-offsets.c:12: In file included from include/linux/compat.h:17: In file included from include/linux/fs.h:33: In file included from include/linux/percpu-rwsem.h:7: In file included from include/linux/rcuwait.h:6: In file included from include/linux/sched/signal.h:6: include/linux/signal.h:98:11: warning: array index 3 is past the end of the array (that has type 'unsigned long[2]') [-Warray-bounds] 98 | return (set->sig[3] | set->sig[2] | | ^ ~ arch/powerpc/include/uapi/asm/signal.h:18:2: note: array 'sig' declared here 18 | unsigned long sig[_NSIG_WORDS]; | ^ In file included from arch/powerpc/kernel/asm-offsets.c:12: In file included from include/linux/compat.h:17: In file included from include/linux/fs.h:33: In file included from include/linux/percpu-rwsem.h:7: In file included from include/linux/rcuwait.h:6: In file included from include/linux/sched/signal.h:6: include/linux/signal.h:98:25: warning: array index 2 is past the end of the array (that has type 'unsigned long[2]') [-Warray-bounds] 98 | return (set->sig[3] | set->sig[2] | | ^ ~ arch/powerpc/include/uapi/asm/signal.h:18:2: note: array 'sig' declared here 18 | unsigned long sig[_NSIG_WORDS]; | ^ In file included from arch/powerpc/kernel/asm-offsets.c:12: In file included from include/linux/compat.h:17: In file included from include/linux/fs.h:33: In file included from include/linux/percpu-rwsem.h:7: In file included from include/linux/rcuwait.h:6: In file included from include/linux/sched/signal.h:6: include/linux/signal.h:114:11: warning: array index 3 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds] 114 | return (set1->sig[3] == set2->sig[3]) && | ^ ~ arch/powerpc/include/uapi/asm/signal.h:18:2: note: array 'sig' declared here 18 | unsigned long sig[_NSIG_WORDS]; | ^ In file included from arch/powerpc/kernel/asm-offsets.c:12: In file included from include/linux/compat.h:17: In file included from include/linux/fs.h:33: In file included from include/linux/percpu-rwsem.h:7: In file included from include/linux/rcuwait.h:6: In file included from include/linux/sched/signal.h:6: include/linux/signal.h:114:27: warning: array index 3 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds] 114 | return (set1->sig[3] == set2->sig[3]) && | ^ ~ arch/powerpc/include/uapi/asm/signal.h:18:2: note: array 'sig' declared here 18 | unsigned long sig[_NSIG_WORDS]; | ^ In file included from arch/powerpc/kernel/asm-offsets.c:12: In file included from include/linux/compat.h:17: In file included from include/linux/fs.h:33: In file included from include/linux/percpu-rwsem.h:7: In file included from include/linux/rcuwait.h:6: In file included from include/linux/sched/signal.h:6: include/linux/signal.h:115:5: warning: array index 2 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds] 115 | (set1->sig[2] == set2->sig[2]) && | ^ ~ arch/powerpc/include/uapi/asm/signal.h:18:2: note: array 'sig' declared here 18 | unsigned long sig[_NSIG_WORDS]; | ^ In file included from arch/powerpc/kernel/asm-offsets.c:12: In file included from include/linux/compat.h:17: In file included from include/linux/fs.h:33: In file included from include/linux/percpu-rwsem.h:7: In file included from include/linux/rcuwait.h:6: In file included from include/linux/sched/signal.h:6: include/linux/signal.h:115:21: warning: array index 2 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds] 115 | (set1->sig[2] == set2->sig[2]) && | ^ ~ arch/powerpc/include/uapi/asm/signal.h:18:2: note: array 'sig' declared here 18 | unsigned long sig[_NSIG_WORDS]; | ^ In file included from arch/powerpc/kernel/asm-offsets.c:12: In file included from include/linux/compat.h:17: In file included from include/linux/fs.h:33: In file included from include/linux/percpu-rwsem.h:7: In file included from include/linux/rcuwait.h:6: In file included from include/linux/sched/signal.h:6: include/linux/signal.h:157:1: warning: array index 3 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds] 157 | _SIG_SET_BINOP(sigorsets, _sig_or) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/signal.h:138:8: note: expanded from macro '_SIG_SET_BINOP' 138 | a3 = a->sig[3]; a2 = a->sig[2]; \ | ^ ~ arch/powerpc/include/uapi/asm/signal.h:18:2: note: array 'sig' declared here 18 | unsigned long sig[_NSIG_WORDS]; | ^ In file included from arch/powerpc/kernel/asm-offsets.c:12: In file included from include/linux/compat.h:17: In file included from include/linux/fs.h:33: In file included from include/linux/percpu-rwsem.h:7: In file included from include/linux/rcuwait.h:6: In file included from include/linux/sched/signal.h:6: include/linux/signal.h:157:1: warning: array index 2 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds] 157 | _SIG_SET_BINOP(sigorsets, _sig_or) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/signal.h:138:24: note: expanded from macro '_SIG_SET_BINOP' 138 | a3 = a->sig[3]; a2 = a->sig[2]; \ vim +/int +8 arch/powerpc/include/asm/preempt.h 6 7 #if defined(CONFIG_PREEMPT_DYNAMIC) && defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY) > 8 DECLARE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched); 9 #endif 10
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index db9f7b2d07bf..b14218344e74 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -272,6 +272,7 @@ config PPC select HAVE_PERF_EVENTS_NMI if PPC64 select HAVE_PERF_REGS select HAVE_PERF_USER_STACK_DUMP + select HAVE_PREEMPT_DYNAMIC_KEY select HAVE_RETHOOK if KPROBES select HAVE_REGS_AND_STACK_ACCESS_API select HAVE_RELIABLE_STACKTRACE diff --git a/arch/powerpc/include/asm/preempt.h b/arch/powerpc/include/asm/preempt.h new file mode 100644 index 000000000000..9d2da4846874 --- /dev/null +++ b/arch/powerpc/include/asm/preempt.h @@ -0,0 +1,11 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_POWERPC_PREEMPT_H +#define __ASM_POWERPC_PREEMPT_H + +#include <asm-generic/preempt.h> + +#if defined(CONFIG_PREEMPT_DYNAMIC) && defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY) +DECLARE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched); +#endif + +#endif /* __ASM_POWERPC_PREEMPT_H */ diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c index 8f4acc55407b..8e2400ba208c 100644 --- a/arch/powerpc/kernel/interrupt.c +++ b/arch/powerpc/kernel/interrupt.c @@ -25,6 +25,10 @@ unsigned long global_dbcr0[NR_CPUS]; #endif +#if defined(CONFIG_PREEMPT_DYNAMIC) && defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY) +DEFINE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched); +#endif + #ifdef CONFIG_PPC_BOOK3S_64 DEFINE_STATIC_KEY_FALSE(interrupt_exit_not_reentrant); static inline bool exit_must_hard_disable(void) @@ -396,7 +400,7 @@ notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs) /* Returning to a kernel context with local irqs enabled. */ WARN_ON_ONCE(!(regs->msr & MSR_EE)); again: - if (IS_ENABLED(CONFIG_PREEMPTION)) { + if (preempt_model_preemptible()) { /* Return to preemptible kernel context */ if (unlikely(read_thread_flags() & _TIF_NEED_RESCHED)) { if (preempt_count() == 0) diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index edf5cabe5dfd..2556fa8ec019 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -266,7 +266,11 @@ static int __die(const char *str, struct pt_regs *regs, long err) printk("%s PAGE_SIZE=%luK%s%s%s%s%s%s %s\n", IS_ENABLED(CONFIG_CPU_LITTLE_ENDIAN) ? "LE" : "BE", PAGE_SIZE / 1024, get_mmu_str(), - IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "", + preempt_model_none() ? "none" : + preempt_model_voluntary() ? "voluntary" : + preempt_model_full() ? "full" : + preempt_model_lazy() ? "lazy" : + "", IS_ENABLED(CONFIG_SMP) ? " SMP" : "", IS_ENABLED(CONFIG_SMP) ? (" NR_CPUS=" __stringify(NR_CPUS)) : "", debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "", diff --git a/arch/powerpc/lib/vmx-helper.c b/arch/powerpc/lib/vmx-helper.c index 58ed6bd613a6..7b069c832ce2 100644 --- a/arch/powerpc/lib/vmx-helper.c +++ b/arch/powerpc/lib/vmx-helper.c @@ -45,7 +45,7 @@ int exit_vmx_usercopy(void) * set and we are preemptible. The hack here is to schedule a * decrementer to fire here and reschedule for us if necessary. */ - if (IS_ENABLED(CONFIG_PREEMPTION) && need_resched()) + if (preempt_model_preemptible() && need_resched()) set_dec(1); return 0; }
Once the lazy preemption is supported, it would be desirable to change the preemption models at runtime. So add support for dynamic preemption using DYNAMIC_KEY. In irq-exit to kernel path, use preempt_model_preemptible for decision. Other way would be using static key based decision. Keeping it simpler since key based change didn't show performance improvement. Also print the right preemption model in __die. ::Tested lightly on Power10 LPAR Performance numbers indicate that, preempt=none(no dynamic) and preempt=none(dynamic) are similar. cat /sys/kernel/debug/sched/preempt (none) voluntary full lazy perf stat -e probe:__cond_resched -a sleep 1 Performance counter stats for 'system wide': 1,253 probe:__cond_resched echo full > /sys/kernel/debug/sched/preempt cat /sys/kernel/debug/sched/preempt none voluntary (full) lazy perf stat -e probe:__cond_resched -a sleep 1 Performance counter stats for 'system wide': 0 probe:__cond_resched Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com> --- arch/powerpc/Kconfig | 1 + arch/powerpc/include/asm/preempt.h | 11 +++++++++++ arch/powerpc/kernel/interrupt.c | 6 +++++- arch/powerpc/kernel/traps.c | 6 +++++- arch/powerpc/lib/vmx-helper.c | 2 +- 5 files changed, 23 insertions(+), 3 deletions(-) create mode 100644 arch/powerpc/include/asm/preempt.h