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Subject: Re: [PATCH v3] RISC-V: Show IPI stats
To:     Anup Patel <anup@brainfault.org>,
        Palmer Dabbelt <palmer@sifive.com>,
        Albert Ou <aou@eecs.berkeley.edu>
Cc:     Christoph Hellwig <hch@infradead.org>,
        "linux-riscv@lists.infradead.org" <linux-riscv@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
References: <20180929062605.12888-1-anup@brainfault.org>
From:   Atish Patra <atish.patra@wdc.com>
Message-ID: <7d40c900-cfb2-f3a0-fce9-0136814781fe@wdc.com>
Date:   Mon, 1 Oct 2018 20:15:08 -0700
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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;

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;

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.

Regards,
Atish