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SubjectRe: [PATCH v3] RISC-V: Show IPI stats
From
On Fri, 28 Sep 2018 23:26:05 PDT (-0700), anup@brainfault.org wrote:
> This patch provides arch_show_interrupts() implementation to
> show IPI stats via /proc/interrupts.
>
> Now the contents of /proc/interrupts" will look like below:
> CPU0 CPU1 CPU2 CPU3
> 8: 17 7 6 14 SiFive PLIC 8 virtio0
> 10: 10 10 9 11 SiFive PLIC 10 ttyS0
> IPI0: 170 673 251 79 Rescheduling interrupts
> IPI1: 1 12 27 1 Function call interrupts
>
> Signed-off-by: Anup Patel <anup@brainfault.org>
>
> Changes since v2:
> - Remove use of IPI_CALL_WAKEUP because it's being removed
>
> Changes since v1:
> - Add stub inline show_ipi_stats() function for !CONFIG_SMP
> - Make ipi_names[] dynamically sized at compile time
> - Minor beautification of ipi_names[] using tabs

Reviewed-by: Palmer Dabbelt <palmer@sifive.com>

This is going in through Atish's patch set.

>
> ---
> arch/riscv/include/asm/smp.h | 9 +++++++++
> arch/riscv/kernel/irq.c | 8 ++++++++
> arch/riscv/kernel/smp.c | 39 +++++++++++++++++++++++++++++-------
> 3 files changed, 49 insertions(+), 7 deletions(-)
>
> diff --git a/arch/riscv/include/asm/smp.h b/arch/riscv/include/asm/smp.h
> index fce312ce3516..5278ae8f1346 100644
> --- a/arch/riscv/include/asm/smp.h
> +++ b/arch/riscv/include/asm/smp.h
> @@ -25,8 +25,13 @@
> extern unsigned long __cpuid_to_hardid_map[NR_CPUS];
> #define cpuid_to_hardid_map(cpu) __cpuid_to_hardid_map[cpu]
>
> +struct seq_file;
> +
> #ifdef CONFIG_SMP
>
> +/* print IPI stats */
> +void show_ipi_stats(struct seq_file *p, int prec);
> +
> /* SMP initialization hook for setup_arch */
> void __init setup_smp(void);
>
> @@ -47,6 +52,10 @@ void riscv_cpuid_to_hartid_mask(const struct cpumask *in, struct cpumask *out);
>
> #else
>
> +static inline void show_ipi_stats(struct seq_file *p, int prec)
> +{
> +}
> +
> static inline int riscv_hartid_to_cpuid(int hartid)
> {
> return 0;
> diff --git a/arch/riscv/kernel/irq.c b/arch/riscv/kernel/irq.c
> index ca4593317e45..48e6b7db83a1 100644
> --- a/arch/riscv/kernel/irq.c
> +++ b/arch/riscv/kernel/irq.c
> @@ -8,6 +8,8 @@
> #include <linux/interrupt.h>
> #include <linux/irqchip.h>
> #include <linux/irqdomain.h>
> +#include <linux/seq_file.h>
> +#include <asm/smp.h>
>
> /*
> * Possible interrupt causes:
> @@ -24,6 +26,12 @@
> */
> #define INTERRUPT_CAUSE_FLAG (1UL << (__riscv_xlen - 1))
>
> +int arch_show_interrupts(struct seq_file *p, int prec)
> +{
> + show_ipi_stats(p, prec);
> + return 0;
> +}
> +
> asmlinkage void __irq_entry do_IRQ(struct pt_regs *regs)
> {
> struct pt_regs *old_regs = set_irq_regs(regs);
> diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
> index 89d95866f562..686fa7a427ff 100644
> --- a/arch/riscv/kernel/smp.c
> +++ b/arch/riscv/kernel/smp.c
> @@ -22,22 +22,24 @@
> #include <linux/interrupt.h>
> #include <linux/smp.h>
> #include <linux/sched.h>
> +#include <linux/seq_file.h>
>
> #include <asm/sbi.h>
> #include <asm/tlbflush.h>
> #include <asm/cacheflush.h>
>
> -/* A collection of single bit ipi messages. */
> -static struct {
> - unsigned long bits ____cacheline_aligned;
> -} ipi_data[NR_CPUS] __cacheline_aligned;
> -
> enum ipi_message_type {
> IPI_RESCHEDULE,
> IPI_CALL_FUNC,
> IPI_MAX
> };
>
> +/* A collection of single bit ipi messages. */
> +static struct {
> + unsigned long stats[IPI_MAX] ____cacheline_aligned;
> + unsigned long bits ____cacheline_aligned;
> +} ipi_data[NR_CPUS] __cacheline_aligned;
> +
> int riscv_hartid_to_cpuid(int hartid)
> {
> int i = -1;
> @@ -67,6 +69,7 @@ int setup_profiling_timer(unsigned int multiplier)
> void riscv_software_interrupt(void)
> {
> unsigned long *pending_ipis = &ipi_data[smp_processor_id()].bits;
> + unsigned long *stats = ipi_data[smp_processor_id()].stats;
>
> /* Clear pending IPI */
> csr_clear(sip, SIE_SSIE);
> @@ -81,11 +84,15 @@ void riscv_software_interrupt(void)
> if (ops == 0)
> return;
>
> - if (ops & (1 << IPI_RESCHEDULE))
> + if (ops & (1 << IPI_RESCHEDULE)) {
> + stats[IPI_RESCHEDULE]++;
> scheduler_ipi();
> + }
>
> - if (ops & (1 << IPI_CALL_FUNC))
> + if (ops & (1 << IPI_CALL_FUNC)) {
> + stats[IPI_CALL_FUNC]++;
> generic_smp_call_function_interrupt();
> + }
>
> BUG_ON((ops >> IPI_MAX) != 0);
>
> @@ -111,6 +118,24 @@ send_ipi_message(const struct cpumask *to_whom, enum ipi_message_type operation)
> sbi_send_ipi(cpumask_bits(&hartid_mask));
> }
>
> +static const char *ipi_names[] = {
> + [IPI_RESCHEDULE] = "Rescheduling interrupts",
> + [IPI_CALL_FUNC] = "Function call interrupts",
> +};
> +
> +void show_ipi_stats(struct seq_file *p, int prec)
> +{
> + unsigned int cpu, i;
> +
> + for (i = 0; i < IPI_MAX; i++) {
> + seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
> + prec >= 4 ? " " : "");
> + for_each_online_cpu(cpu)
> + seq_printf(p, "%10lu ", ipi_data[cpu].stats[i]);
> + seq_printf(p, " %s\n", ipi_names[i]);
> + }
> +}
> +
> void arch_send_call_function_ipi_mask(struct cpumask *mask)
> {
> send_ipi_message(mask, IPI_CALL_FUNC);

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