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Message-ID: <CAKfTPtCePxOMGtwz_8XNJZyZK4iqDb32WageUWXYuBuQWrh5Yw@mail.gmail.com>
Date: Mon, 4 Jul 2011 08:52:40 +0200
From: Vincent Guittot <vincent.guittot@...aro.org>
To: Russell King - ARM Linux <linux@....linux.org.uk>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linaro-dev@...ts.linaro.org, patches@...aro.org
Subject: Re: [PATCH v4] Add ARM cpu topology definition
On 1 July 2011 23:09, Russell King - ARM Linux <linux@....linux.org.uk> wrote:
> On Fri, Jul 01, 2011 at 07:43:30AM +0200, Vincent Guittot wrote:
>> Changes since v3 :
>> * Update the format of printk message
>> * Remove blank line
>
> Can I trouble you to check the patch for more instances of the 'blank line
> at end of function' thing... Also, let's get rid of unnecessary parens.
>
ok, I will update the patch with your comments
>> diff --git a/arch/arm/include/asm/topology.h b/arch/arm/include/asm/topology.h
>> index accbd7c..63a7454 100644
>> --- a/arch/arm/include/asm/topology.h
>> +++ b/arch/arm/include/asm/topology.h
>> @@ -1,6 +1,39 @@
>> #ifndef _ASM_ARM_TOPOLOGY_H
>> #define _ASM_ARM_TOPOLOGY_H
>>
>> +#ifdef CONFIG_ARM_CPU_TOPOLOGY
>> +
>> +#include <linux/cpumask.h>
>> +
>> +struct cputopo_arm {
>> + int thread_id;
>> + int core_id;
>> + int socket_id;
>> + cpumask_t thread_sibling;
>> + cpumask_t core_sibling;
>> +};
>> +
>> +extern struct cputopo_arm cpu_topology[NR_CPUS];
>> +
>> +#define topology_physical_package_id(cpu) (cpu_topology[cpu].socket_id)
>> +#define topology_core_id(cpu) (cpu_topology[cpu].core_id)
>> +#define topology_core_cpumask(cpu) (&(cpu_topology[cpu].core_sibling))
>> +#define topology_thread_cpumask(cpu) (&(cpu_topology[cpu].thread_sibling))
>
> The inner-most parens aren't required.
>
>> +
>> +#define mc_capable() (cpu_topology[0].socket_id != -1)
>> +#define smt_capable() (cpu_topology[0].thread_id != -1)
>> +
>> +void init_cpu_topology(void);
>> +void store_cpu_topology(unsigned int cpuid);
>> +const struct cpumask *cpu_coregroup_mask(unsigned int cpu);
>> +
>> +#else
>> +
>> +static inline void init_cpu_topology(void) { };
>> +static inline void store_cpu_topology(unsigned int cpuid) { };
>
> Functions don't need a ; after the }
>
>> +
>> +#endif
>> +
>> #include <asm-generic/topology.h>
>>
>> #endif /* _ASM_ARM_TOPOLOGY_H */
>> diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
>> index a5b31af..816a481 100644
>> --- a/arch/arm/kernel/Makefile
>> +++ b/arch/arm/kernel/Makefile
>> @@ -61,6 +61,7 @@ obj-$(CONFIG_IWMMXT) += iwmmxt.o
>> obj-$(CONFIG_CPU_HAS_PMU) += pmu.o
>> obj-$(CONFIG_HW_PERF_EVENTS) += perf_event.o
>> AFLAGS_iwmmxt.o := -Wa,-mcpu=iwmmxt
>> +obj-$(CONFIG_ARM_CPU_TOPOLOGY) += topology.o
>>
>> ifneq ($(CONFIG_ARCH_EBSA110),y)
>> obj-y += io.o
>> diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
>> index 344e52b..3e8dc3b 100644
>> --- a/arch/arm/kernel/smp.c
>> +++ b/arch/arm/kernel/smp.c
>> @@ -31,6 +31,7 @@
>> #include <asm/cacheflush.h>
>> #include <asm/cpu.h>
>> #include <asm/cputype.h>
>> +#include <asm/topology.h>
>> #include <asm/mmu_context.h>
>> #include <asm/pgtable.h>
>> #include <asm/pgalloc.h>
>> @@ -268,6 +269,9 @@ static void __cpuinit smp_store_cpu_info(unsigned int cpuid)
>> struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
>>
>> cpu_info->loops_per_jiffy = loops_per_jiffy;
>> +
>> + store_cpu_topology(cpuid);
>> +
>
> Don't need this blank line.
>
>> }
>>
>> /*
>> @@ -354,6 +358,8 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
>> {
>> unsigned int ncores = num_possible_cpus();
>>
>> + init_cpu_topology();
>> +
>> smp_store_cpu_info(smp_processor_id());
>>
>> /*
>> diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c
>> new file mode 100644
>> index 0000000..e8f3b95
>> --- /dev/null
>> +++ b/arch/arm/kernel/topology.c
>> @@ -0,0 +1,149 @@
>> +/*
>> + * arch/arm/kernel/topology.c
>> + *
>> + * Copyright (C) 2011 Linaro Limited.
>> + * Written by: Vincent Guittot
>> + *
>> + * based on arch/sh/kernel/topology.c
>> + *
>> + * This file is subject to the terms and conditions of the GNU General Public
>> + * License. See the file "COPYING" in the main directory of this archive
>> + * for more details.
>> + */
>> +
>> +#include <linux/cpu.h>
>> +#include <linux/cpumask.h>
>> +#include <linux/init.h>
>> +#include <linux/percpu.h>
>> +#include <linux/node.h>
>> +#include <linux/nodemask.h>
>> +#include <linux/sched.h>
>> +
>> +#include <asm/cputype.h>
>> +#include <asm/topology.h>
>> +
>> +#define MPIDR_SMP_BITMASK (0x3 << 30)
>> +#define MPIDR_SMP_VALUE (0x2 << 30)
>> +
>> +#define MPIDR_MT_BITMASK (0x1 << 24)
>> +
>> +/*
>> + * These masks reflect the current use of the affinity levels.
>> + * The affinity level can be up to 16 bits according to ARM ARM
>> + */
>> +
>> +#define MPIDR_LEVEL0_MASK 0x3
>> +#define MPIDR_LEVEL0_SHIFT 0
>> +
>> +#define MPIDR_LEVEL1_MASK 0xF
>> +#define MPIDR_LEVEL1_SHIFT 8
>> +
>> +#define MPIDR_LEVEL2_MASK 0xFF
>> +#define MPIDR_LEVEL2_SHIFT 16
>> +
>> +struct cputopo_arm cpu_topology[NR_CPUS];
>> +
>> +const struct cpumask *cpu_coregroup_mask(unsigned int cpu)
>> +{
>> + return &(cpu_topology[cpu].core_sibling);
>
> These parens aren't required.
>
>> +}
>> +
>> +/*
>> + * store_cpu_topology is called at boot when only one cpu is running
>> + * and with the mutex cpu_hotplug.lock locked, when several cpus have booted,
>> + * which prevents simultaneous write access to cpu_topology array
>> + */
>> +void store_cpu_topology(unsigned int cpuid)
>> +{
>> + struct cputopo_arm *cpuid_topo = &(cpu_topology[cpuid]);
>
> Neither are these.
>
>> + unsigned int mpidr;
>> + unsigned int cpu;
>> +
>> + /* If the cpu topology has been already set, just return */
>> + if (cpuid_topo->core_id != -1)
>> + return;
>> +
>> + mpidr = read_cpuid_mpidr();
>> +
>> + /* create cpu topology mapping */
>> + if ((mpidr & MPIDR_SMP_BITMASK) == MPIDR_SMP_VALUE) {
>> + /*
>> + * This is a multiprocessor system
>> + * multiprocessor format & multiprocessor mode field are set
>> + */
>> +
>> + if (mpidr & MPIDR_MT_BITMASK) {
>> + /* core performance interdependency */
>> + cpuid_topo->thread_id = ((mpidr >> MPIDR_LEVEL0_SHIFT)
>> + & MPIDR_LEVEL0_MASK);
>> + cpuid_topo->core_id = ((mpidr >> MPIDR_LEVEL1_SHIFT)
>> + & MPIDR_LEVEL1_MASK);
>> + cpuid_topo->socket_id = ((mpidr >> MPIDR_LEVEL2_SHIFT)
>> + & MPIDR_LEVEL2_MASK);
>
> Outer set aren't required.
>
>> + } else {
>> + /* largely independent cores */
>> + cpuid_topo->thread_id = -1;
>> + cpuid_topo->core_id = ((mpidr >> MPIDR_LEVEL0_SHIFT)
>> + & MPIDR_LEVEL0_MASK);
>> + cpuid_topo->socket_id = ((mpidr >> MPIDR_LEVEL1_SHIFT)
>> + & MPIDR_LEVEL1_MASK);
>
> Outer set aren't required.
>
>> + }
>> + } else {
>> + /*
>> + * This is an uniprocessor system
>> + * we are in multiprocessor format but uniprocessor system
>> + * or in the old uniprocessor format
>> + */
>> +
>
> This blank line isn't necessary.
>
>> + cpuid_topo->thread_id = -1;
>> + cpuid_topo->core_id = 0;
>> + cpuid_topo->socket_id = -1;
>> + }
>> +
>> + /* update core and thread sibling masks */
>> + for_each_possible_cpu(cpu) {
>> + struct cputopo_arm *cpu_topo = &(cpu_topology[cpu]);
>
> Parens not required.
>
>> +
>> + if (cpuid_topo->socket_id == cpu_topo->socket_id) {
>> + cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
>> + if (cpu != cpuid)
>> + cpumask_set_cpu(cpu,
>> + &cpuid_topo->core_sibling);
>> +
>> + if (cpuid_topo->core_id == cpu_topo->core_id) {
>> + cpumask_set_cpu(cpuid,
>> + &cpu_topo->thread_sibling);
>> + if (cpu != cpuid)
>> + cpumask_set_cpu(cpu,
>> + &cpuid_topo->thread_sibling);
>> + }
>> + }
>> + }
>> + smp_wmb();
>> +
>> + printk(KERN_INFO "CPU%u: thread %d, cpu %d, socket %d, mpidr %x\n",
>> + cpuid, cpu_topology[cpuid].thread_id,
>> + cpu_topology[cpuid].core_id,
>> + cpu_topology[cpuid].socket_id, mpidr);
>
> Thanks for changing that.
>
>> +}
>> +
>> +/*
>> + * init_cpu_topology is called at boot when only one cpu is running
>> + * which prevent simultaneous write access to cpu_topology array
>> + */
>> +void init_cpu_topology(void)
>> +{
>> + unsigned int cpu;
>> +
>> + /* init core mask */
>> + for_each_possible_cpu(cpu) {
>> + struct cputopo_arm *cpu_topo = &(cpu_topology[cpu]);
>> +
>> + cpu_topo->thread_id = -1;
>> + cpu_topo->core_id = -1;
>> + cpu_topo->socket_id = -1;
>> + cpumask_clear(&cpu_topo->core_sibling);
>> + cpumask_clear(&cpu_topo->thread_sibling);
>> + }
>> + smp_wmb();
>> +}
>
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