From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754854Ab3DLS4T (ORCPT ); Fri, 12 Apr 2013 14:56:19 -0400 Received: from www.linutronix.de ([62.245.132.108]:55995 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752491Ab3DLS4R (ORCPT ); Fri, 12 Apr 2013 14:56:17 -0400 Date: Fri, 12 Apr 2013 20:56:10 +0200 (CEST) From: Thomas Gleixner To: Sam Ravnborg cc: David Miller , srivatsa.bhat@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, rusty@rustcorp.com.au, paulmck@linux.vnet.ibm.com, mingo@elte.hu, peterz@infradead.org, magnus.damm@gmail.com Subject: Re: [PATCH v2] sparc: Use generic idle loop In-Reply-To: <20130411193850.GA2330@merkur.ravnborg.org> Message-ID: References: <20130401090620.GA24861@merkur.ravnborg.org> <5162B92E.6020703@linux.vnet.ibm.com> <20130408171035.GA27264@merkur.ravnborg.org> <20130408.152449.169732563685022388.davem@davemloft.net> <20130411193850.GA2330@merkur.ravnborg.org> User-Agent: Alpine 2.02 (LFD 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 11 Apr 2013, Sam Ravnborg wrote: > Add generic cpu_idle support > > sparc32: > - replace call to cpu_idle() with cpu_startup_entry() > - add arch_cpu_idle() > > sparc64: > - smp_callin() now include cpu_startup_entry() call so we can > skip calling cpu_idle from assembler > - add arch_cpu_idle() and arch_cpu_idle_dead() Nice ! If Dave acks it, I'll pick it up Thanks, tglx > Signed-off-by: Sam Ravnborg > Reviewed-by: "Srivatsa S. Bhat" > Cc: David S. Miller > --- > v1->v2: > - simplified arch_cpu_idle() - former sparc64_yield() based on comments from Srivatsa > - dropped TIF_POLLING_NRFLAG handling > - dropped smp_mb__after_clear_bit() - this is done in generic code using rmb() > - dropped the out-most while (!need_resched() && !cpu_is_offline(cpu)) > - always enable irq on exit in arch_cpu_idle (both sparc32 and sparc64) > - added comment from davem why we need to clear IE bit in sparc64 arch_cpu_idle() > > Sam > > > diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig > index 3d361f2..ee5eacc 100644 > --- a/arch/sparc/Kconfig > +++ b/arch/sparc/Kconfig > @@ -37,6 +37,7 @@ config SPARC > select GENERIC_SMP_IDLE_THREAD > select GENERIC_CMOS_UPDATE > select GENERIC_CLOCKEVENTS > + select GENERIC_IDLE_LOOP > select GENERIC_STRNCPY_FROM_USER > select GENERIC_STRNLEN_USER > select MODULES_USE_ELF_RELA > diff --git a/arch/sparc/kernel/hvtramp.S b/arch/sparc/kernel/hvtramp.S > index 9365432..605c960 100644 > --- a/arch/sparc/kernel/hvtramp.S > +++ b/arch/sparc/kernel/hvtramp.S > @@ -128,8 +128,7 @@ hv_cpu_startup: > > call smp_callin > nop > - call cpu_idle > - mov 0, %o0 > + > call cpu_panic > nop > > diff --git a/arch/sparc/kernel/process_32.c b/arch/sparc/kernel/process_32.c > index 62eede1..c852410 100644 > --- a/arch/sparc/kernel/process_32.c > +++ b/arch/sparc/kernel/process_32.c > @@ -64,23 +64,12 @@ extern void fpsave(unsigned long *, unsigned long *, void *, unsigned long *); > struct task_struct *last_task_used_math = NULL; > struct thread_info *current_set[NR_CPUS]; > > -/* > - * the idle loop on a Sparc... ;) > - */ > -void cpu_idle(void) > +/* Idle loop support. */ > +void arch_cpu_idle(void) > { > - set_thread_flag(TIF_POLLING_NRFLAG); > - > - /* endless idle loop with no priority at all */ > - for (;;) { > - while (!need_resched()) { > - if (sparc_idle) > - (*sparc_idle)(); > - else > - cpu_relax(); > - } > - schedule_preempt_disabled(); > - } > + if (sparc_idle) > + (*sparc_idle)(); > + local_irq_enable(); > } > > /* XXX cli/sti -> local_irq_xxx here, check this works once SMP is fixed. */ > diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c > index cdb80b2..9fbf0d1 100644 > --- a/arch/sparc/kernel/process_64.c > +++ b/arch/sparc/kernel/process_64.c > @@ -52,20 +52,17 @@ > > #include "kstack.h" > > -static void sparc64_yield(int cpu) > +/* Idle loop support on sparc64. */ > +void arch_cpu_idle(void) > { > if (tlb_type != hypervisor) { > touch_nmi_watchdog(); > - return; > - } > - > - clear_thread_flag(TIF_POLLING_NRFLAG); > - smp_mb__after_clear_bit(); > - > - while (!need_resched() && !cpu_is_offline(cpu)) { > + } else { > unsigned long pstate; > > - /* Disable interrupts. */ > + /* The sun4v sleeping code requires that we have PSTATE.IE cleared over > + * the cpu sleep hypervisor call. > + */ > __asm__ __volatile__( > "rdpr %%pstate, %0\n\t" > "andn %0, %1, %0\n\t" > @@ -73,7 +70,7 @@ static void sparc64_yield(int cpu) > : "=&r" (pstate) > : "i" (PSTATE_IE)); > > - if (!need_resched() && !cpu_is_offline(cpu)) > + if (!need_resched() && !cpu_is_offline(smp_processor_id())) > sun4v_cpu_yield(); > > /* Re-enable interrupts. */ > @@ -84,36 +81,16 @@ static void sparc64_yield(int cpu) > : "=&r" (pstate) > : "i" (PSTATE_IE)); > } > - > - set_thread_flag(TIF_POLLING_NRFLAG); > + local_irq_enable(); > } > > -/* The idle loop on sparc64. */ > -void cpu_idle(void) > -{ > - int cpu = smp_processor_id(); > - > - set_thread_flag(TIF_POLLING_NRFLAG); > - > - while(1) { > - tick_nohz_idle_enter(); > - rcu_idle_enter(); > - > - while (!need_resched() && !cpu_is_offline(cpu)) > - sparc64_yield(cpu); > - > - rcu_idle_exit(); > - tick_nohz_idle_exit(); > - > #ifdef CONFIG_HOTPLUG_CPU > - if (cpu_is_offline(cpu)) { > - sched_preempt_enable_no_resched(); > - cpu_play_dead(); > - } > -#endif > - schedule_preempt_disabled(); > - } > +void arch_cpu_idle_dead() > +{ > + sched_preempt_enable_no_resched(); > + cpu_play_dead(); > } > +#endif > > #ifdef CONFIG_COMPAT > static void show_regwindow32(struct pt_regs *regs) > diff --git a/arch/sparc/kernel/smp_32.c b/arch/sparc/kernel/smp_32.c > index 9e7e6d7..e3f2b81 100644 > --- a/arch/sparc/kernel/smp_32.c > +++ b/arch/sparc/kernel/smp_32.c > @@ -369,7 +369,7 @@ void __cpuinit sparc_start_secondary(void *arg) > local_irq_enable(); > > wmb(); > - cpu_idle(); > + cpu_startup_entry(CPUHP_ONLINE); > > /* We should never reach here! */ > BUG(); > diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c > index 537eb66..c025ffc 100644 > --- a/arch/sparc/kernel/smp_64.c > +++ b/arch/sparc/kernel/smp_64.c > @@ -127,6 +127,8 @@ void __cpuinit smp_callin(void) > > /* idle thread is expected to have preempt disabled */ > preempt_disable(); > + > + cpu_startup_entry(CPUHP_ONLINE); > } > > void cpu_panic(void) > diff --git a/arch/sparc/kernel/trampoline_64.S b/arch/sparc/kernel/trampoline_64.S > index da1b781..2e973a2 100644 > --- a/arch/sparc/kernel/trampoline_64.S > +++ b/arch/sparc/kernel/trampoline_64.S > @@ -407,8 +407,7 @@ after_lock_tlb: > > call smp_callin > nop > - call cpu_idle > - mov 0, %o0 > + > call cpu_panic > nop > 1: b,a,pt %xcc, 1b >