diff options
author | Hong H. Pham <hong.pham@windriver.com> | 2009-06-04 02:10:11 -0700 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2009-06-16 04:56:28 -0700 |
commit | 280ff97494e0fef4124bee5c52e39b23a18dd283 (patch) | |
tree | e906ca3c5e0a6238882d181ab5b01fb3f40ba5df /arch/sparc | |
parent | 4fd78a5f1edf62ab1ca3d23efee4a8a336edb2b6 (diff) | |
download | kernel_samsung_tuna-280ff97494e0fef4124bee5c52e39b23a18dd283.zip kernel_samsung_tuna-280ff97494e0fef4124bee5c52e39b23a18dd283.tar.gz kernel_samsung_tuna-280ff97494e0fef4124bee5c52e39b23a18dd283.tar.bz2 |
sparc64: fix and optimize irq distribution
irq_choose_cpu() should compare the affinity mask against cpu_online_map
rather than CPU_MASK_ALL, since irq_select_affinity() sets the interrupt's
affinity mask to cpu_online_map "and" CPU_MASK_ALL (which ends up being
just cpu_online_map). The mask comparison in irq_choose_cpu() will always
fail since the two masks are not the same. So the CPU chosen is the first CPU
in the intersection of cpu_online_map and CPU_MASK_ALL, which is always CPU0.
That means all interrupts are reassigned to CPU0...
Distributing interrupts to CPUs in a linearly increasing round robin fashion
is not optimal for the UltraSPARC T1/T2. Also, the irq_rover in
irq_choose_cpu() causes an interrupt to be assigned to a different
processor each time the interrupt is allocated and released. This may lead
to an unbalanced distribution over time.
A static mapping of interrupts to processors is done to optimize and balance
interrupt distribution. For the T1/T2, interrupts are spread to different
cores first, and then to strands within a core.
The following is some benchmarks showing the effects of interrupt
distribution on a T2. The test was done with iperf using a pair of T5220
boxes, each with a 10GBe NIU (XAUI) connected back to back.
TCP | Stock Linear RR IRQ Optimized IRQ
Streams | 2.6.30-rc5 Distribution Distribution
| GBits/sec GBits/sec GBits/sec
--------+-----------------------------------------
1 0.839 0.862 0.868
8 1.16 4.96 5.88
16 1.15 6.40 8.04
100 1.09 7.28 8.68
Signed-off-by: Hong H. Pham <hong.pham@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/sparc')
-rw-r--r-- | arch/sparc/kernel/Makefile | 1 | ||||
-rw-r--r-- | arch/sparc/kernel/cpumap.c | 431 | ||||
-rw-r--r-- | arch/sparc/kernel/cpumap.h | 16 | ||||
-rw-r--r-- | arch/sparc/kernel/irq_64.c | 29 | ||||
-rw-r--r-- | arch/sparc/kernel/smp_64.c | 4 |
5 files changed, 456 insertions, 25 deletions
diff --git a/arch/sparc/kernel/Makefile b/arch/sparc/kernel/Makefile index 54742e5..47029c6 100644 --- a/arch/sparc/kernel/Makefile +++ b/arch/sparc/kernel/Makefile @@ -54,6 +54,7 @@ obj-$(CONFIG_SPARC64) += sstate.o obj-$(CONFIG_SPARC64) += mdesc.o obj-$(CONFIG_SPARC64) += pcr.o obj-$(CONFIG_SPARC64) += nmi.o +obj-$(CONFIG_SPARC64_SMP) += cpumap.o # sparc32 do not use GENERIC_HARDIRQS but uses the generic devres implementation obj-$(CONFIG_SPARC32) += devres.o diff --git a/arch/sparc/kernel/cpumap.c b/arch/sparc/kernel/cpumap.c new file mode 100644 index 0000000..7430ed0 --- /dev/null +++ b/arch/sparc/kernel/cpumap.c @@ -0,0 +1,431 @@ +/* cpumap.c: used for optimizing CPU assignment + * + * Copyright (C) 2009 Hong H. Pham <hong.pham@windriver.com> + */ + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/cpumask.h> +#include <linux/spinlock.h> +#include <asm/cpudata.h> +#include "cpumap.h" + + +enum { + CPUINFO_LVL_ROOT = 0, + CPUINFO_LVL_NODE, + CPUINFO_LVL_CORE, + CPUINFO_LVL_PROC, + CPUINFO_LVL_MAX, +}; + +enum { + ROVER_NO_OP = 0, + /* Increment rover every time level is visited */ + ROVER_INC_ON_VISIT = 1 << 0, + /* Increment parent's rover every time rover wraps around */ + ROVER_INC_PARENT_ON_LOOP = 1 << 1, +}; + +struct cpuinfo_node { + int id; + int level; + int num_cpus; /* Number of CPUs in this hierarchy */ + int parent_index; + int child_start; /* Array index of the first child node */ + int child_end; /* Array index of the last child node */ + int rover; /* Child node iterator */ +}; + +struct cpuinfo_level { + int start_index; /* Index of first node of a level in a cpuinfo tree */ + int end_index; /* Index of last node of a level in a cpuinfo tree */ + int num_nodes; /* Number of nodes in a level in a cpuinfo tree */ +}; + +struct cpuinfo_tree { + int total_nodes; + + /* Offsets into nodes[] for each level of the tree */ + struct cpuinfo_level level[CPUINFO_LVL_MAX]; + struct cpuinfo_node nodes[0]; +}; + + +static struct cpuinfo_tree *cpuinfo_tree; + +static u16 cpu_distribution_map[NR_CPUS]; +static DEFINE_SPINLOCK(cpu_map_lock); + + +/* Niagara optimized cpuinfo tree traversal. */ +static const int niagara_iterate_method[] = { + [CPUINFO_LVL_ROOT] = ROVER_NO_OP, + + /* Strands (or virtual CPUs) within a core may not run concurrently + * on the Niagara, as instruction pipeline(s) are shared. Distribute + * work to strands in different cores first for better concurrency. + * Go to next NUMA node when all cores are used. + */ + [CPUINFO_LVL_NODE] = ROVER_INC_ON_VISIT|ROVER_INC_PARENT_ON_LOOP, + + /* Strands are grouped together by proc_id in cpuinfo_sparc, i.e. + * a proc_id represents an instruction pipeline. Distribute work to + * strands in different proc_id groups if the core has multiple + * instruction pipelines (e.g. the Niagara 2/2+ has two). + */ + [CPUINFO_LVL_CORE] = ROVER_INC_ON_VISIT, + + /* Pick the next strand in the proc_id group. */ + [CPUINFO_LVL_PROC] = ROVER_INC_ON_VISIT, +}; + +/* Generic cpuinfo tree traversal. Distribute work round robin across NUMA + * nodes. + */ +static const int generic_iterate_method[] = { + [CPUINFO_LVL_ROOT] = ROVER_INC_ON_VISIT, + [CPUINFO_LVL_NODE] = ROVER_NO_OP, + [CPUINFO_LVL_CORE] = ROVER_INC_PARENT_ON_LOOP, + [CPUINFO_LVL_PROC] = ROVER_INC_ON_VISIT|ROVER_INC_PARENT_ON_LOOP, +}; + + +static int cpuinfo_id(int cpu, int level) +{ + int id; + + switch (level) { + case CPUINFO_LVL_ROOT: + id = 0; + break; + case CPUINFO_LVL_NODE: + id = cpu_to_node(cpu); + break; + case CPUINFO_LVL_CORE: + id = cpu_data(cpu).core_id; + break; + case CPUINFO_LVL_PROC: + id = cpu_data(cpu).proc_id; + break; + default: + id = -EINVAL; + } + return id; +} + +/* + * Enumerate the CPU information in __cpu_data to determine the start index, + * end index, and number of nodes for each level in the cpuinfo tree. The + * total number of cpuinfo nodes required to build the tree is returned. + */ +static int enumerate_cpuinfo_nodes(struct cpuinfo_level *tree_level) +{ + int prev_id[CPUINFO_LVL_MAX]; + int i, n, num_nodes; + + for (i = CPUINFO_LVL_ROOT; i < CPUINFO_LVL_MAX; i++) { + struct cpuinfo_level *lv = &tree_level[i]; + + prev_id[i] = -1; + lv->start_index = lv->end_index = lv->num_nodes = 0; + } + + num_nodes = 1; /* Include the root node */ + + for (i = 0; i < num_possible_cpus(); i++) { + if (!cpu_online(i)) + continue; + + n = cpuinfo_id(i, CPUINFO_LVL_NODE); + if (n > prev_id[CPUINFO_LVL_NODE]) { + tree_level[CPUINFO_LVL_NODE].num_nodes++; + prev_id[CPUINFO_LVL_NODE] = n; + num_nodes++; + } + n = cpuinfo_id(i, CPUINFO_LVL_CORE); + if (n > prev_id[CPUINFO_LVL_CORE]) { + tree_level[CPUINFO_LVL_CORE].num_nodes++; + prev_id[CPUINFO_LVL_CORE] = n; + num_nodes++; + } + n = cpuinfo_id(i, CPUINFO_LVL_PROC); + if (n > prev_id[CPUINFO_LVL_PROC]) { + tree_level[CPUINFO_LVL_PROC].num_nodes++; + prev_id[CPUINFO_LVL_PROC] = n; + num_nodes++; + } + } + + tree_level[CPUINFO_LVL_ROOT].num_nodes = 1; + + n = tree_level[CPUINFO_LVL_NODE].num_nodes; + tree_level[CPUINFO_LVL_NODE].start_index = 1; + tree_level[CPUINFO_LVL_NODE].end_index = n; + + n++; + tree_level[CPUINFO_LVL_CORE].start_index = n; + n += tree_level[CPUINFO_LVL_CORE].num_nodes; + tree_level[CPUINFO_LVL_CORE].end_index = n - 1; + + tree_level[CPUINFO_LVL_PROC].start_index = n; + n += tree_level[CPUINFO_LVL_PROC].num_nodes; + tree_level[CPUINFO_LVL_PROC].end_index = n - 1; + + return num_nodes; +} + +/* Build a tree representation of the CPU hierarchy using the per CPU + * information in __cpu_data. Entries in __cpu_data[0..NR_CPUS] are + * assumed to be sorted in ascending order based on node, core_id, and + * proc_id (in order of significance). + */ +static struct cpuinfo_tree *build_cpuinfo_tree(void) +{ + struct cpuinfo_tree *new_tree; + struct cpuinfo_node *node; + struct cpuinfo_level tmp_level[CPUINFO_LVL_MAX]; + int num_cpus[CPUINFO_LVL_MAX]; + int level_rover[CPUINFO_LVL_MAX]; + int prev_id[CPUINFO_LVL_MAX]; + int n, id, cpu, prev_cpu, last_cpu, level; + + n = enumerate_cpuinfo_nodes(tmp_level); + + new_tree = kzalloc(sizeof(struct cpuinfo_tree) + + (sizeof(struct cpuinfo_node) * n), GFP_ATOMIC); + if (!new_tree) + return NULL; + + new_tree->total_nodes = n; + memcpy(&new_tree->level, tmp_level, sizeof(tmp_level)); + + prev_cpu = cpu = first_cpu(cpu_online_map); + + /* Initialize all levels in the tree with the first CPU */ + for (level = CPUINFO_LVL_PROC; level >= CPUINFO_LVL_ROOT; level--) { + n = new_tree->level[level].start_index; + + level_rover[level] = n; + node = &new_tree->nodes[n]; + + id = cpuinfo_id(cpu, level); + if (unlikely(id < 0)) { + kfree(new_tree); + return NULL; + } + node->id = id; + node->level = level; + node->num_cpus = 1; + + node->parent_index = (level > CPUINFO_LVL_ROOT) + ? new_tree->level[level - 1].start_index : -1; + + node->child_start = node->child_end = node->rover = + (level == CPUINFO_LVL_PROC) + ? cpu : new_tree->level[level + 1].start_index; + + prev_id[level] = node->id; + num_cpus[level] = 1; + } + + for (last_cpu = (num_possible_cpus() - 1); last_cpu >= 0; last_cpu--) { + if (cpu_online(last_cpu)) + break; + } + + while (++cpu <= last_cpu) { + if (!cpu_online(cpu)) + continue; + + for (level = CPUINFO_LVL_PROC; level >= CPUINFO_LVL_ROOT; + level--) { + id = cpuinfo_id(cpu, level); + if (unlikely(id < 0)) { + kfree(new_tree); + return NULL; + } + + if ((id != prev_id[level]) || (cpu == last_cpu)) { + prev_id[level] = id; + node = &new_tree->nodes[level_rover[level]]; + node->num_cpus = num_cpus[level]; + num_cpus[level] = 1; + + if (cpu == last_cpu) + node->num_cpus++; + + /* Connect tree node to parent */ + if (level == CPUINFO_LVL_ROOT) + node->parent_index = -1; + else + node->parent_index = + level_rover[level - 1]; + + if (level == CPUINFO_LVL_PROC) { + node->child_end = + (cpu == last_cpu) ? cpu : prev_cpu; + } else { + node->child_end = + level_rover[level + 1] - 1; + } + + /* Initialize the next node in the same level */ + n = ++level_rover[level]; + if (n <= new_tree->level[level].end_index) { + node = &new_tree->nodes[n]; + node->id = id; + node->level = level; + + /* Connect node to child */ + node->child_start = node->child_end = + node->rover = + (level == CPUINFO_LVL_PROC) + ? cpu : level_rover[level + 1]; + } + } else + num_cpus[level]++; + } + prev_cpu = cpu; + } + + return new_tree; +} + +static void increment_rover(struct cpuinfo_tree *t, int node_index, + int root_index, const int *rover_inc_table) +{ + struct cpuinfo_node *node = &t->nodes[node_index]; + int top_level, level; + + top_level = t->nodes[root_index].level; + for (level = node->level; level >= top_level; level--) { + node->rover++; + if (node->rover <= node->child_end) + return; + + node->rover = node->child_start; + /* If parent's rover does not need to be adjusted, stop here. */ + if ((level == top_level) || + !(rover_inc_table[level] & ROVER_INC_PARENT_ON_LOOP)) + return; + + node = &t->nodes[node->parent_index]; + } +} + +static int iterate_cpu(struct cpuinfo_tree *t, unsigned int root_index) +{ + const int *rover_inc_table; + int level, new_index, index = root_index; + + switch (sun4v_chip_type) { + case SUN4V_CHIP_NIAGARA1: + case SUN4V_CHIP_NIAGARA2: + rover_inc_table = niagara_iterate_method; + break; + default: + rover_inc_table = generic_iterate_method; + } + + for (level = t->nodes[root_index].level; level < CPUINFO_LVL_MAX; + level++) { + new_index = t->nodes[index].rover; + if (rover_inc_table[level] & ROVER_INC_ON_VISIT) + increment_rover(t, index, root_index, rover_inc_table); + + index = new_index; + } + return index; +} + +static void _cpu_map_rebuild(void) +{ + int i; + + if (cpuinfo_tree) { + kfree(cpuinfo_tree); + cpuinfo_tree = NULL; + } + + cpuinfo_tree = build_cpuinfo_tree(); + if (!cpuinfo_tree) + return; + + /* Build CPU distribution map that spans all online CPUs. No need + * to check if the CPU is online, as that is done when the cpuinfo + * tree is being built. + */ + for (i = 0; i < cpuinfo_tree->nodes[0].num_cpus; i++) + cpu_distribution_map[i] = iterate_cpu(cpuinfo_tree, 0); +} + +/* Fallback if the cpuinfo tree could not be built. CPU mapping is linear + * round robin. + */ +static int simple_map_to_cpu(unsigned int index) +{ + int i, end, cpu_rover; + + cpu_rover = 0; + end = index % num_online_cpus(); + for (i = 0; i < num_possible_cpus(); i++) { + if (cpu_online(cpu_rover)) { + if (cpu_rover >= end) + return cpu_rover; + + cpu_rover++; + } + } + + /* Impossible, since num_online_cpus() <= num_possible_cpus() */ + return first_cpu(cpu_online_map); +} + +static int _map_to_cpu(unsigned int index) +{ + struct cpuinfo_node *root_node; + + if (unlikely(!cpuinfo_tree)) { + _cpu_map_rebuild(); + if (!cpuinfo_tree) + return simple_map_to_cpu(index); + } + + root_node = &cpuinfo_tree->nodes[0]; +#ifdef CONFIG_HOTPLUG_CPU + if (unlikely(root_node->num_cpus != num_online_cpus())) { + _cpu_map_rebuild(); + if (!cpuinfo_tree) + return simple_map_to_cpu(index); + } +#endif + return cpu_distribution_map[index % root_node->num_cpus]; +} + +int map_to_cpu(unsigned int index) +{ + int mapped_cpu; + unsigned long flag; + + spin_lock_irqsave(&cpu_map_lock, flag); + mapped_cpu = _map_to_cpu(index); + +#ifdef CONFIG_HOTPLUG_CPU + while (unlikely(!cpu_online(mapped_cpu))) + mapped_cpu = _map_to_cpu(index); +#endif + spin_unlock_irqrestore(&cpu_map_lock, flag); + return mapped_cpu; +} +EXPORT_SYMBOL(map_to_cpu); + +void cpu_map_rebuild(void) +{ + unsigned long flag; + + spin_lock_irqsave(&cpu_map_lock, flag); + _cpu_map_rebuild(); + spin_unlock_irqrestore(&cpu_map_lock, flag); +} diff --git a/arch/sparc/kernel/cpumap.h b/arch/sparc/kernel/cpumap.h new file mode 100644 index 0000000..e639880 --- /dev/null +++ b/arch/sparc/kernel/cpumap.h @@ -0,0 +1,16 @@ +#ifndef _CPUMAP_H +#define _CPUMAP_H + +#ifdef CONFIG_SMP +extern void cpu_map_rebuild(void); +extern int map_to_cpu(unsigned int index); +#define cpu_map_init() cpu_map_rebuild() +#else +#define cpu_map_init() do {} while (0) +static inline int map_to_cpu(unsigned int index) +{ + return raw_smp_processor_id(); +} +#endif + +#endif diff --git a/arch/sparc/kernel/irq_64.c b/arch/sparc/kernel/irq_64.c index e5e78f9..bd07505 100644 --- a/arch/sparc/kernel/irq_64.c +++ b/arch/sparc/kernel/irq_64.c @@ -45,6 +45,7 @@ #include <asm/cacheflush.h> #include "entry.h" +#include "cpumap.h" #define NUM_IVECS (IMAP_INR + 1) @@ -256,35 +257,13 @@ static int irq_choose_cpu(unsigned int virt_irq) int cpuid; cpumask_copy(&mask, irq_desc[virt_irq].affinity); - if (cpus_equal(mask, CPU_MASK_ALL)) { - static int irq_rover; - static DEFINE_SPINLOCK(irq_rover_lock); - unsigned long flags; - - /* Round-robin distribution... */ - do_round_robin: - spin_lock_irqsave(&irq_rover_lock, flags); - - while (!cpu_online(irq_rover)) { - if (++irq_rover >= nr_cpu_ids) - irq_rover = 0; - } - cpuid = irq_rover; - do { - if (++irq_rover >= nr_cpu_ids) - irq_rover = 0; - } while (!cpu_online(irq_rover)); - - spin_unlock_irqrestore(&irq_rover_lock, flags); + if (cpus_equal(mask, cpu_online_map)) { + cpuid = map_to_cpu(virt_irq); } else { cpumask_t tmp; cpus_and(tmp, cpu_online_map, mask); - - if (cpus_empty(tmp)) - goto do_round_robin; - - cpuid = first_cpu(tmp); + cpuid = cpus_empty(tmp) ? map_to_cpu(virt_irq) : first_cpu(tmp); } return cpuid; diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c index 1de47d2..cfb3d06 100644 --- a/arch/sparc/kernel/smp_64.c +++ b/arch/sparc/kernel/smp_64.c @@ -48,6 +48,8 @@ #include <asm/ldc.h> #include <asm/hypervisor.h> +#include "cpumap.h" + int sparc64_multi_core __read_mostly; DEFINE_PER_CPU(cpumask_t, cpu_sibling_map) = CPU_MASK_NONE; @@ -1314,6 +1316,8 @@ int __cpu_disable(void) cpu_clear(cpu, cpu_online_map); ipi_call_unlock(); + cpu_map_rebuild(); + return 0; } |