On Fri, Jul 24, 2015 at 04:14:22PM +0100, Alex Smith wrote:
> The majority of SMP platforms handle their IPIs through do_IRQ()
> which calls irq_{enter/exit}(). When a call function IPI is received,
> smp_call_function_interrupt() is called which also calls
> irq_{enter,exit}(), meaning irq_count is raised twice.
>
> When tick broadcasting is used (which is implemented via a call
> function IPI), this incorrectly causes all CPU idle time on the core
> receiving broadcast ticks to be accounted as time spent servicing
> IRQs, as account_process_tick() will account as such if irq_count is
> greater than 1. This results in 100% CPU usage being reported on a
> core which receives its ticks via broadcast.
>
> This patch removes the SMP smp_call_function_interrupt() wrapper which
> calls irq_{enter,exit}(). Platforms which handle their IPIs through
> do_IRQ() now call generic_smp_call_function_interrupt() directly to
> avoid incrementing irq_count a second time. Platforms which don't
> (loongson, sgi-ip27, sibyte) call generic_smp_call_function_interrupt()
> wrapped in irq_{enter,exit}().
>
> Signed-off-by: Alex Smith <alex.smith@xxxxxxxxxx>
> ---
> arch/mips/cavium-octeon/smp.c | 2 +-
> arch/mips/include/asm/smp.h | 2 --
> arch/mips/kernel/smp-bmips.c | 4 ++--
> arch/mips/kernel/smp.c | 10 ----------
> arch/mips/lantiq/irq.c | 2 +-
> arch/mips/loongson64/loongson-3/smp.c | 7 +++++--
> arch/mips/mti-malta/malta-int.c | 2 +-
> arch/mips/netlogic/common/smp.c | 2 +-
> arch/mips/paravirt/paravirt-smp.c | 2 +-
> arch/mips/pmcs-msp71xx/msp_smp.c | 2 +-
> arch/mips/sgi-ip27/ip27-irq.c | 8 ++++++--
> arch/mips/sibyte/bcm1480/smp.c | 9 +++++----
> arch/mips/sibyte/sb1250/smp.c | 7 +++++--
> 13 files changed, 29 insertions(+), 30 deletions(-)
Hi Alex,
I think you'll need to catch the case in drivers/irqchip/irq-mips-gic.c
too.
Thanks,
Paul
> diff --git a/arch/mips/cavium-octeon/smp.c b/arch/mips/cavium-octeon/smp.c
> index 56f5d080ef9d..b7fa9ae28c36 100644
> --- a/arch/mips/cavium-octeon/smp.c
> +++ b/arch/mips/cavium-octeon/smp.c
> @@ -42,7 +42,7 @@ static irqreturn_t mailbox_interrupt(int irq, void *dev_id)
> cvmx_write_csr(CVMX_CIU_MBOX_CLRX(coreid), action);
>
> if (action & SMP_CALL_FUNCTION)
> - smp_call_function_interrupt();
> + generic_smp_call_function_interrupt();
> if (action & SMP_RESCHEDULE_YOURSELF)
> scheduler_ipi();
>
> diff --git a/arch/mips/include/asm/smp.h b/arch/mips/include/asm/smp.h
> index 16f1ea9ab191..03722d4326a1 100644
> --- a/arch/mips/include/asm/smp.h
> +++ b/arch/mips/include/asm/smp.h
> @@ -83,8 +83,6 @@ static inline void __cpu_die(unsigned int cpu)
> extern void play_dead(void);
> #endif
>
> -extern asmlinkage void smp_call_function_interrupt(void);
> -
> static inline void arch_send_call_function_single_ipi(int cpu)
> {
> extern struct plat_smp_ops *mp_ops; /* private */
> diff --git a/arch/mips/kernel/smp-bmips.c b/arch/mips/kernel/smp-bmips.c
> index 336708ae5c5b..78cf8c2f1de0 100644
> --- a/arch/mips/kernel/smp-bmips.c
> +++ b/arch/mips/kernel/smp-bmips.c
> @@ -284,7 +284,7 @@ static irqreturn_t bmips5000_ipi_interrupt(int irq, void *dev_id)
> if (action == 0)
> scheduler_ipi();
> else
> - smp_call_function_interrupt();
> + generic_smp_call_function_interrupt();
>
> return IRQ_HANDLED;
> }
> @@ -336,7 +336,7 @@ static irqreturn_t bmips43xx_ipi_interrupt(int irq, void *dev_id)
> if (action & SMP_RESCHEDULE_YOURSELF)
> scheduler_ipi();
> if (action & SMP_CALL_FUNCTION)
> - smp_call_function_interrupt();
> + generic_smp_call_function_interrupt();
>
> return IRQ_HANDLED;
> }
> diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
> index d0744cc77ea7..a31896c33716 100644
> --- a/arch/mips/kernel/smp.c
> +++ b/arch/mips/kernel/smp.c
> @@ -192,16 +192,6 @@ asmlinkage void start_secondary(void)
> cpu_startup_entry(CPUHP_ONLINE);
> }
>
> -/*
> - * Call into both interrupt handlers, as we share the IPI for them
> - */
> -void __irq_entry smp_call_function_interrupt(void)
> -{
> - irq_enter();
> - generic_smp_call_function_interrupt();
> - irq_exit();
> -}
> -
> static void stop_this_cpu(void *dummy)
> {
> /*
> diff --git a/arch/mips/lantiq/irq.c b/arch/mips/lantiq/irq.c
> index 6ab10573490d..be18648cb8c8 100644
> --- a/arch/mips/lantiq/irq.c
> +++ b/arch/mips/lantiq/irq.c
> @@ -293,7 +293,7 @@ static irqreturn_t ipi_resched_interrupt(int irq, void *dev_id)
>
> static irqreturn_t ipi_call_interrupt(int irq, void *dev_id)
> {
> - smp_call_function_interrupt();
> + generic_smp_call_function_interrupt();
> return IRQ_HANDLED;
> }
>
> diff --git a/arch/mips/loongson64/loongson-3/smp.c b/arch/mips/loongson64/loongson-3/smp.c
> index 509877c6e9d9..1a4738a8f2d3 100644
> --- a/arch/mips/loongson64/loongson-3/smp.c
> +++ b/arch/mips/loongson64/loongson-3/smp.c
> @@ -266,8 +266,11 @@ void loongson3_ipi_interrupt(struct pt_regs *regs)
> if (action & SMP_RESCHEDULE_YOURSELF)
> scheduler_ipi();
>
> - if (action & SMP_CALL_FUNCTION)
> - smp_call_function_interrupt();
> + if (action & SMP_CALL_FUNCTION) {
> + irq_enter();
> + generic_smp_call_function_interrupt();
> + irq_exit();
> + }
>
> if (action & SMP_ASK_C0COUNT) {
> BUG_ON(cpu != 0);
> diff --git a/arch/mips/mti-malta/malta-int.c b/arch/mips/mti-malta/malta-int.c
> index d1392f8f5811..fa8f591f3713 100644
> --- a/arch/mips/mti-malta/malta-int.c
> +++ b/arch/mips/mti-malta/malta-int.c
> @@ -222,7 +222,7 @@ static irqreturn_t ipi_resched_interrupt(int irq, void *dev_id)
>
> static irqreturn_t ipi_call_interrupt(int irq, void *dev_id)
> {
> - smp_call_function_interrupt();
> + generic_smp_call_function_interrupt();
>
> return IRQ_HANDLED;
> }
> diff --git a/arch/mips/netlogic/common/smp.c b/arch/mips/netlogic/common/smp.c
> index dc3e327fbbac..f5fff228b347 100644
> --- a/arch/mips/netlogic/common/smp.c
> +++ b/arch/mips/netlogic/common/smp.c
> @@ -86,7 +86,7 @@ void nlm_smp_function_ipi_handler(unsigned int irq, struct irq_desc *desc)
> {
> clear_c0_eimr(irq);
> ack_c0_eirr(irq);
> - smp_call_function_interrupt();
> + generic_smp_call_function_interrupt();
> set_c0_eimr(irq);
> }
>
> diff --git a/arch/mips/paravirt/paravirt-smp.c b/arch/mips/paravirt/paravirt-smp.c
> index 42181c7105df..f8d3e081b2eb 100644
> --- a/arch/mips/paravirt/paravirt-smp.c
> +++ b/arch/mips/paravirt/paravirt-smp.c
> @@ -114,7 +114,7 @@ static irqreturn_t paravirt_reched_interrupt(int irq, void *dev_id)
>
> static irqreturn_t paravirt_function_interrupt(int irq, void *dev_id)
> {
> - smp_call_function_interrupt();
> + generic_smp_call_function_interrupt();
> return IRQ_HANDLED;
> }
>
> diff --git a/arch/mips/pmcs-msp71xx/msp_smp.c b/arch/mips/pmcs-msp71xx/msp_smp.c
> index 10170580a2de..ffa0f7101a97 100644
> --- a/arch/mips/pmcs-msp71xx/msp_smp.c
> +++ b/arch/mips/pmcs-msp71xx/msp_smp.c
> @@ -44,7 +44,7 @@ static irqreturn_t ipi_resched_interrupt(int irq, void *dev_id)
>
> static irqreturn_t ipi_call_interrupt(int irq, void *dev_id)
> {
> - smp_call_function_interrupt();
> + generic_smp_call_function_interrupt();
>
> return IRQ_HANDLED;
> }
> diff --git a/arch/mips/sgi-ip27/ip27-irq.c b/arch/mips/sgi-ip27/ip27-irq.c
> index 3fbaef97a1b8..16ec4e12daa3 100644
> --- a/arch/mips/sgi-ip27/ip27-irq.c
> +++ b/arch/mips/sgi-ip27/ip27-irq.c
> @@ -107,10 +107,14 @@ static void ip27_do_irq_mask0(void)
> scheduler_ipi();
> } else if (pend0 & (1UL << CPU_CALL_A_IRQ)) {
> LOCAL_HUB_CLR_INTR(CPU_CALL_A_IRQ);
> - smp_call_function_interrupt();
> + irq_enter();
> + generic_smp_call_function_interrupt();
> + irq_exit();
> } else if (pend0 & (1UL << CPU_CALL_B_IRQ)) {
> LOCAL_HUB_CLR_INTR(CPU_CALL_B_IRQ);
> - smp_call_function_interrupt();
> + irq_enter();
> + generic_smp_call_function_interrupt();
> + irq_exit();
> } else
> #endif
> {
> diff --git a/arch/mips/sibyte/bcm1480/smp.c b/arch/mips/sibyte/bcm1480/smp.c
> index af7d44edd9a8..4c71aea25663 100644
> --- a/arch/mips/sibyte/bcm1480/smp.c
> +++ b/arch/mips/sibyte/bcm1480/smp.c
> @@ -29,8 +29,6 @@
> #include <asm/sibyte/bcm1480_regs.h>
> #include <asm/sibyte/bcm1480_int.h>
>
> -extern void smp_call_function_interrupt(void);
> -
> /*
> * These are routines for dealing with the bcm1480 smp capabilities
> * independent of board/firmware
> @@ -184,6 +182,9 @@ void bcm1480_mailbox_interrupt(void)
> if (action & SMP_RESCHEDULE_YOURSELF)
> scheduler_ipi();
>
> - if (action & SMP_CALL_FUNCTION)
> - smp_call_function_interrupt();
> + if (action & SMP_CALL_FUNCTION) {
> + irq_enter();
> + generic_smp_call_function_interrupt();
> + irq_exit();
> + }
> }
> diff --git a/arch/mips/sibyte/sb1250/smp.c b/arch/mips/sibyte/sb1250/smp.c
> index c0c4b3f88a08..1cf66f5ff23d 100644
> --- a/arch/mips/sibyte/sb1250/smp.c
> +++ b/arch/mips/sibyte/sb1250/smp.c
> @@ -172,6 +172,9 @@ void sb1250_mailbox_interrupt(void)
> if (action & SMP_RESCHEDULE_YOURSELF)
> scheduler_ipi();
>
> - if (action & SMP_CALL_FUNCTION)
> - smp_call_function_interrupt();
> + if (action & SMP_CALL_FUNCTION) {
> + irq_enter();
> + generic_smp_call_function_interrupt();
> + irq_exit();
> + }
> }
> --
> 2.4.6
>
>
