Re: [PATCH v3] RISC-V: Show IPI stats

[Anup Patel]

On Tue, Oct 2, 2018 at 8:45 AM Atish Patra <atish.patra@xxxxxxx> wrote:
>
> On 9/28/18 11:26 PM, Anup Patel 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@xxxxxxxxxxxxxx>
> >
> > 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
> >
> > ---
> >   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);
> >
> some checkpatch errors.
>
> patches/smp_cleanup/0014-RISC-V-Show-IPI-stats.patch
> ----------------------------------------------------
> WARNING: Missing a blank line after declarations
> #115: FILE: arch/riscv/kernel/smp.c:40:
> +       unsigned long stats[IPI_MAX] ____cacheline_aligned;
> +       unsigned long bits ____cacheline_aligned;

This was already there in existing code.

>
> WARNING: usage of NR_CPUS is often wrong - consider using
> cpu_possible(), num_possible_cpus(), for_each_possible_cpu(), etc
> #116: FILE: arch/riscv/kernel/smp.c:41:
> +} ipi_data[NR_CPUS] __cacheline_aligned;

Even this was already there in existing code.

>
> WARNING: static const char * array should probably be static const char
> * const
> #151: FILE: arch/riscv/kernel/smp.c:121:
> +static const char *ipi_names[] = {
>
> total: 0 errors, 3 warnings, 120 lines checked
>
> Let me know if they were ignored on purpose.
>

Yes, this one was added by this patch.

Do you want me to send revised patch?

Regards,
Anup