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

[Atish Patra <atish.patra@wdc.com>]

On 10/1/18 8:29 PM, Anup Patel wrote:
> On Tue, Oct 2, 2018 at 8:45 AM Atish Patra <atish.patra@wdc.com> 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@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
>>>
>>> ---
>>>    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?
> 

Nope. That's just a one line fix. I fixed it and submitted the patch as 
part of my v6.

I will send a separate patch fix for the patch errors introduced by the 
existing code as the fix was bit involved.

Regards,
Atish
> Regards,
> Anup
> 


Regards,
Atish