On 18/03/14 17:56, Vincent Guittot wrote:

We replace the old way to configure the scheduler topology with a new method which enables a platform to declare additionnal level (if needed).

We still have a default topology table definition that can be used by platform that don't want more level than the SMT, MC, CPU and NUMA ones. This table can be overwritten by an arch which wants to add new level where a load balance make sense like BOOK or powergating level.

For each level, we need a function pointer that returns cpumask for each cpu, a function pointer that returns the flags for the level and a name. Only flags that describe topology, can be set by an architecture. The current topology flags are: SD_SHARE_CPUPOWER SD_SHARE_PKG_RESOURCES SD_NUMA SD_ASYM_PACKING

Then, each level must be a subset on the next one. The build sequence of the sched_domain will take care of removing useless levels like those with 1 CPU and those with the same CPU span and relevant information for load balancing than its child.

Signed-off-by: Vincent Guittot vincent.guittot@linaro.org

arch/ia64/include/asm/topology.h | 24 ---- arch/s390/include/asm/topology.h | 2 - arch/tile/include/asm/topology.h | 33 ------ include/linux/sched.h | 48 ++++++++ include/linux/topology.h | 128 +++------------------ kernel/sched/core.c | 235 ++++++++++++++++++++------------------- 6 files changed, 183 insertions(+), 287 deletions(-)

diff --git a/arch/ia64/include/asm/topology.h b/arch/ia64/include/asm/topology.h index 5cb55a1..3202aa7 100644 --- a/arch/ia64/include/asm/topology.h +++ b/arch/ia64/include/asm/topology.h @@ -46,30 +46,6 @@

void build_cpu_to_node_map(void);

-#define SD_CPU_INIT (struct sched_domain) { \

•   .parent                 = NULL,                 \
  

•   .child                  = NULL,                 \
  

•   .groups                 = NULL,                 \
  

•   .min_interval           = 1,                    \
  

•   .max_interval           = 4,                    \
  

•   .busy_factor            = 64,                   \
  

•   .imbalance_pct          = 125,                  \
  

•   .cache_nice_tries       = 2,                    \
  

•   .busy_idx               = 2,                    \
  

•   .idle_idx               = 1,                    \
  

•   .newidle_idx            = 0,                    \
  

•   .wake_idx               = 0,                    \
  

•   .forkexec_idx           = 0,                    \
  

•   .flags                  = SD_LOAD_BALANCE       \
  

•                           | SD_BALANCE_NEWIDLE    \
  

•                           | SD_BALANCE_EXEC       \
  

•                           | SD_BALANCE_FORK       \
  

•                           | SD_WAKE_AFFINE,       \
  

•   .last_balance           = jiffies,              \
  

•   .balance_interval       = 1,                    \
  

•   .nr_balance_failed      = 0,                    \
  

-}

#endif /* CONFIG_NUMA */

#ifdef CONFIG_SMP diff --git a/arch/s390/include/asm/topology.h b/arch/s390/include/asm/topology.h index 05425b1..07763bd 100644 --- a/arch/s390/include/asm/topology.h +++ b/arch/s390/include/asm/topology.h @@ -64,8 +64,6 @@ static inline void s390_init_cpu_topology(void) }; #endif

-#define SD_BOOK_INIT SD_CPU_INIT

#include <asm-generic/topology.h>

#endif /* _ASM_S390_TOPOLOGY_H */ diff --git a/arch/tile/include/asm/topology.h b/arch/tile/include/asm/topology.h index d15c0d8..9383118 100644 --- a/arch/tile/include/asm/topology.h +++ b/arch/tile/include/asm/topology.h @@ -44,39 +44,6 @@ static inline const struct cpumask *cpumask_of_node(int node) /* For now, use numa node -1 for global allocation. */ #define pcibus_to_node(bus) ((void)(bus), -1)

-/*

• • TILE architecture has many cores integrated in one processor, so we need
• • setup bigger balance_interval for both CPU/NODE scheduling domains to
• • reduce process scheduling costs.
• */

-/* sched_domains SD_CPU_INIT for TILE architecture */ -#define SD_CPU_INIT (struct sched_domain) { \

•   .min_interval           = 4,                                    \
  

•   .max_interval           = 128,                                  \
  

•   .busy_factor            = 64,                                   \
  

•   .imbalance_pct          = 125,                                  \
  

•   .cache_nice_tries       = 1,                                    \
  

•   .busy_idx               = 2,                                    \
  

•   .idle_idx               = 1,                                    \
  

•   .newidle_idx            = 0,                                    \
  

•   .wake_idx               = 0,                                    \
  

•   .forkexec_idx           = 0,                                    \
  

•                                                                   \
  

•   .flags                  = 1*SD_LOAD_BALANCE                     \
  

•                           | 1*SD_BALANCE_NEWIDLE                  \
  

•                           | 1*SD_BALANCE_EXEC                     \
  

•                           | 1*SD_BALANCE_FORK                     \
  

•                           | 0*SD_BALANCE_WAKE                     \
  

•                           | 0*SD_WAKE_AFFINE                      \
  

•                           | 0*SD_SHARE_CPUPOWER                   \
  

•                           | 0*SD_SHARE_PKG_RESOURCES              \
  

•                           | 0*SD_SERIALIZE                        \
  

•                           ,                                       \
  

•   .last_balance           = jiffies,                              \
  

•   .balance_interval       = 32,                                   \
  

-}

/* By definition, we create nodes based on online memory. */ #define node_has_online_mem(nid) 1

diff --git a/include/linux/sched.h b/include/linux/sched.h index 825ed83..4db592a 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -870,6 +870,20 @@ enum cpu_idle_type {

extern int __weak arch_sd_sibiling_asym_packing(void);

+#ifdef CONFIG_SCHED_SMT +static inline const int cpu_smt_flags(void) +{

•   return SD_SHARE_CPUPOWER | SD_SHARE_PKG_RESOURCES;
  

+} +#endif

+#ifdef CONFIG_SCHED_MC +static inline const int cpu_core_flags(void) +{

•   return SD_SHARE_PKG_RESOURCES;
  

+} +#endif

struct sched_domain_attr { int relax_domain_level; }; @@ -976,6 +990,38 @@ void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms);

bool cpus_share_cache(int this_cpu, int that_cpu);

+typedef const struct cpumask *(*sched_domain_mask_f)(int cpu); +typedef const int (*sched_domain_flags_f)(void);

+#define SDTL_OVERLAP 0x01

+struct sd_data {

•   struct sched_domain **__percpu sd;
  

•   struct sched_group **__percpu sg;
  

•   struct sched_group_power **__percpu sgp;
  

+};

+struct sched_domain_topology_level {

•   sched_domain_mask_f mask;
  

•   sched_domain_flags_f sd_flags;
  

•   int                 flags;
  

•   int                 numa_level;
  

•   struct sd_data      data;
  

+#ifdef CONFIG_SCHED_DEBUG

•   char                *name;
  

+#endif +};

+extern struct sched_domain_topology_level *sched_domain_topology;

+extern void set_sched_topology(struct sched_domain_topology_level *tl);

+#ifdef CONFIG_SCHED_DEBUG +# define SD_INIT_NAME(type) .name = #type +#else +# define SD_INIT_NAME(type) +#endif

#else /* CONFIG_SMP */

struct sched_domain_attr; @@ -991,6 +1037,8 @@ static inline bool cpus_share_cache(int this_cpu, int that_cpu) return true; }

+static inline void set_sched_topology(struct sched_domain_topology_level *tl) { }

#endif /* !CONFIG_SMP */

diff --git a/include/linux/topology.h b/include/linux/topology.h index 12ae6ce..3a9db05 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -66,121 +66,6 @@ int arch_update_cpu_topology(void); #define PENALTY_FOR_NODE_WITH_CPUS (1) #endif

-/*

• • Below are the 3 major initializers used in building sched_domains:
• • SD_SIBLING_INIT, for SMT domains
• • SD_CPU_INIT, for SMP domains
• • Any architecture that cares to do any tuning to these values should do so
• • by defining their own arch-specific initializer in include/asm/topology.h.
• • A definition there will automagically override these default initializers
• • and allow arch-specific performance tuning of sched_domains.
• • (Only non-zero and non-null fields need be specified.)
• */

-#ifdef CONFIG_SCHED_SMT -/* MCD - Do we really need this? It is always on if CONFIG_SCHED_SMT is,

• • so can't we drop this in favor of CONFIG_SCHED_SMT?
• */

-#define ARCH_HAS_SCHED_WAKE_IDLE -/* Common values for SMT siblings */ -#ifndef SD_SIBLING_INIT -#define SD_SIBLING_INIT (struct sched_domain) { \

•   .min_interval           = 1,                                    \
  

•   .max_interval           = 2,                                    \
  

•   .busy_factor            = 64,                                   \
  

•   .imbalance_pct          = 110,                                  \
  

•                                                                   \
  

•   .flags                  = 1*SD_LOAD_BALANCE                     \
  

•                           | 1*SD_BALANCE_NEWIDLE                  \
  

•                           | 1*SD_BALANCE_EXEC                     \
  

•                           | 1*SD_BALANCE_FORK                     \
  

•                           | 0*SD_BALANCE_WAKE                     \
  

•                           | 1*SD_WAKE_AFFINE                      \
  

•                           | 1*SD_SHARE_CPUPOWER                   \
  

•                           | 1*SD_SHARE_PKG_RESOURCES              \
  

•                           | 0*SD_SERIALIZE                        \
  

•                           | 0*SD_PREFER_SIBLING                   \
  

•                           | arch_sd_sibling_asym_packing()        \
  

•                           ,                                       \
  

•   .last_balance           = jiffies,                              \
  

•   .balance_interval       = 1,                                    \
  

•   .smt_gain               = 1178, /* 15% */                       \
  

•   .max_newidle_lb_cost    = 0,                                    \
  

•   .next_decay_max_lb_cost = jiffies,                              \
  

-} -#endif -#endif /* CONFIG_SCHED_SMT */

-#ifdef CONFIG_SCHED_MC -/* Common values for MC siblings. for now mostly derived from SD_CPU_INIT */ -#ifndef SD_MC_INIT -#define SD_MC_INIT (struct sched_domain) { \

•   .min_interval           = 1,                                    \
  

•   .max_interval           = 4,                                    \
  

•   .busy_factor            = 64,                                   \
  

•   .imbalance_pct          = 125,                                  \
  

•   .cache_nice_tries       = 1,                                    \
  

•   .busy_idx               = 2,                                    \
  

•   .wake_idx               = 0,                                    \
  

•   .forkexec_idx           = 0,                                    \
  

•                                                                   \
  

•   .flags                  = 1*SD_LOAD_BALANCE                     \
  

•                           | 1*SD_BALANCE_NEWIDLE                  \
  

•                           | 1*SD_BALANCE_EXEC                     \
  

•                           | 1*SD_BALANCE_FORK                     \
  

•                           | 0*SD_BALANCE_WAKE                     \
  

•                           | 1*SD_WAKE_AFFINE                      \
  

•                           | 0*SD_SHARE_CPUPOWER                   \
  

•                           | 1*SD_SHARE_PKG_RESOURCES              \
  

•                           | 0*SD_SERIALIZE                        \
  

•                           ,                                       \
  

•   .last_balance           = jiffies,                              \
  

•   .balance_interval       = 1,                                    \
  

•   .max_newidle_lb_cost    = 0,                                    \
  

•   .next_decay_max_lb_cost = jiffies,                              \
  

-} -#endif -#endif /* CONFIG_SCHED_MC */

-/* Common values for CPUs */ -#ifndef SD_CPU_INIT -#define SD_CPU_INIT (struct sched_domain) { \

•   .min_interval           = 1,                                    \
  

•   .max_interval           = 4,                                    \
  

•   .busy_factor            = 64,                                   \
  

•   .imbalance_pct          = 125,                                  \
  

•   .cache_nice_tries       = 1,                                    \
  

•   .busy_idx               = 2,                                    \
  

•   .idle_idx               = 1,                                    \
  

•   .newidle_idx            = 0,                                    \
  

•   .wake_idx               = 0,                                    \
  

•   .forkexec_idx           = 0,                                    \
  

•                                                                   \
  

•   .flags                  = 1*SD_LOAD_BALANCE                     \
  

•                           | 1*SD_BALANCE_NEWIDLE                  \
  

•                           | 1*SD_BALANCE_EXEC                     \
  

•                           | 1*SD_BALANCE_FORK                     \
  

•                           | 0*SD_BALANCE_WAKE                     \
  

•                           | 1*SD_WAKE_AFFINE                      \
  

•                           | 0*SD_SHARE_CPUPOWER                   \
  

•                           | 0*SD_SHARE_PKG_RESOURCES              \
  

•                           | 0*SD_SERIALIZE                        \
  

•                           | 1*SD_PREFER_SIBLING                   \
  

•                           ,                                       \
  

•   .last_balance           = jiffies,                              \
  

•   .balance_interval       = 1,                                    \
  

•   .max_newidle_lb_cost    = 0,                                    \
  

•   .next_decay_max_lb_cost = jiffies,                              \
  

-} -#endif

-#ifdef CONFIG_SCHED_BOOK -#ifndef SD_BOOK_INIT -#error Please define an appropriate SD_BOOK_INIT in include/asm/topology.h!!! -#endif -#endif /* CONFIG_SCHED_BOOK */

#ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID DECLARE_PER_CPU(int, numa_node);

@@ -295,4 +180,17 @@ static inline int cpu_to_mem(int cpu) #define topology_core_cpumask(cpu) cpumask_of(cpu) #endif

+#ifdef CONFIG_SCHED_SMT +static inline const struct cpumask *cpu_smt_mask(int cpu) +{

•   return topology_thread_cpumask(cpu);
  

+} +#endif

+static inline const struct cpumask *cpu_cpu_mask(int cpu) +{

•   return cpumask_of_node(cpu_to_node(cpu));
  

+}

#endif /* _LINUX_TOPOLOGY_H */ diff --git a/kernel/sched/core.c b/kernel/sched/core.c index ae365aa..3397bcb 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5603,17 +5603,6 @@ static int __init isolated_cpu_setup(char *str)

__setup("isolcpus=", isolated_cpu_setup);

-static const struct cpumask *cpu_cpu_mask(int cpu) -{

•   return cpumask_of_node(cpu_to_node(cpu));
  

-}

-struct sd_data {

•   struct sched_domain **__percpu sd;
  

•   struct sched_group **__percpu sg;
  

•   struct sched_group_power **__percpu sgp;
  

-};

struct s_data { struct sched_domain ** __percpu sd; struct root_domain *rd; @@ -5626,21 +5615,6 @@ enum s_alloc { sa_none, };

-struct sched_domain_topology_level;

-typedef struct sched_domain *(*sched_domain_init_f)(struct sched_domain_topology_level *tl, int cpu); -typedef const struct cpumask *(*sched_domain_mask_f)(int cpu);

-#define SDTL_OVERLAP 0x01

-struct sched_domain_topology_level {

•   sched_domain_init_f init;
  

•   sched_domain_mask_f mask;
  

•   int                 flags;
  

•   int                 numa_level;
  

•   struct sd_data      data;
  

-};

/*

• Build an iteration mask that can exclude certain CPUs from the upwards
• domain traversal.

@@ -5869,34 +5843,6 @@ int __weak arch_sd_sibling_asym_packing(void)

• Non-inlined to reduce accumulated stack pressure in build_sched_domains()

*/

-#ifdef CONFIG_SCHED_DEBUG -# define SD_INIT_NAME(sd, type) sd->name = #type -#else -# define SD_INIT_NAME(sd, type) do { } while (0) -#endif

-#define SD_INIT_FUNC(type) \ -static noinline struct sched_domain * \ -sd_init_##type(struct sched_domain_topology_level *tl, int cpu) \ -{ \

•   struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu);       \
  

•   *sd = SD_##type##_INIT;                                         \
  

•   SD_INIT_NAME(sd, type);                                         \
  

•   sd->private = &tl->data;                                        \
  

•   return sd;                                                      \
  

-}

-SD_INIT_FUNC(CPU) -#ifdef CONFIG_SCHED_SMT

• SD_INIT_FUNC(SIBLING)

-#endif -#ifdef CONFIG_SCHED_MC

• SD_INIT_FUNC(MC)

-#endif -#ifdef CONFIG_SCHED_BOOK

• SD_INIT_FUNC(BOOK)

-#endif

static int default_relax_domain_level = -1; int sched_domain_level_max;

@@ -5984,97 +5930,156 @@ static void claim_allocations(int cpu, struct sched_domain *sd) *per_cpu_ptr(sdd->sgp, cpu) = NULL; }

-#ifdef CONFIG_SCHED_SMT -static const struct cpumask *cpu_smt_mask(int cpu) -{

•   return topology_thread_cpumask(cpu);
  

-} -#endif

-/*

• • Topology list, bottom-up.
• */

-static struct sched_domain_topology_level default_topology[] = { -#ifdef CONFIG_SCHED_SMT

•   { sd_init_SIBLING, cpu_smt_mask, },
  

-#endif -#ifdef CONFIG_SCHED_MC

•   { sd_init_MC, cpu_coregroup_mask, },
  

-#endif -#ifdef CONFIG_SCHED_BOOK

•   { sd_init_BOOK, cpu_book_mask, },
  

-#endif

•   { sd_init_CPU, cpu_cpu_mask, },
  

•   { NULL, },
  

-};

-static struct sched_domain_topology_level *sched_domain_topology = default_topology;

-#define for_each_sd_topology(tl) \

•   for (tl = sched_domain_topology; tl->init; tl++)
  

#ifdef CONFIG_NUMA

static int sched_domains_numa_levels; static int *sched_domains_numa_distance; static struct cpumask ***sched_domains_numa_masks; static int sched_domains_curr_level; +#endif

-static inline int sd_local_flags(int level) -{

•   if (sched_domains_numa_distance[level] > RECLAIM_DISTANCE)
  

•           return 0;
  

•   return SD_BALANCE_EXEC | SD_BALANCE_FORK | SD_WAKE_AFFINE;
  

-} +/*

• • SD_flags allowed in topology descriptions.
• • SD_SHARE_CPUPOWER - describes SMT topologies
• • SD_SHARE_PKG_RESOURCES - describes shared caches
• • SD_NUMA - describes NUMA topologies
• • Odd one out:
• • SD_ASYM_PACKING - describes SMT quirks
• */

+#define TOPOLOGY_SD_FLAGS \

•   (SD_SHARE_CPUPOWER |            \
  

•    SD_SHARE_PKG_RESOURCES |       \
  

•    SD_NUMA |                      \
  

•    SD_ASYM_PACKING)
  
  

static struct sched_domain * -sd_numa_init(struct sched_domain_topology_level *tl, int cpu) +sd_init(struct sched_domain_topology_level *tl, int cpu) { struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu);

•   int level = tl->numa_level;
  

•   int sd_weight = cpumask_weight(
  

•                   sched_domains_numa_masks[level][cpu_to_node(cpu)]);
  

•   int sd_weight, sd_flags = 0;
  

+#ifdef CONFIG_NUMA

•   /*
  

•    * Ugly hack to pass state to sd_numa_mask()...
  

•    */
  

•   sched_domains_curr_level = tl->numa_level;
  

+#endif

•   sd_weight = cpumask_weight(tl->mask(cpu));
  

•   if (tl->sd_flags)
  

•           sd_flags = (*tl->sd_flags)();
  

•   if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
  

•                   "wrong sd_flags in topology description\n"))
  

•           sd_flags &= ~TOPOLOGY_SD_FLAGS;
  
    *sd = (struct sched_domain){
            .min_interval           = sd_weight,
            .max_interval           = 2*sd_weight,
            .busy_factor            = 32,
            .imbalance_pct          = 125,
  

•           .cache_nice_tries       = 2,
  

•           .busy_idx               = 3,
  

•           .idle_idx               = 2,
  

•           .cache_nice_tries       = 0,
  

•           .busy_idx               = 0,
  

•           .idle_idx               = 0,
            .newidle_idx            = 0,
            .wake_idx               = 0,
            .forkexec_idx           = 0,
  
            .flags                  = 1*SD_LOAD_BALANCE
                                    | 1*SD_BALANCE_NEWIDLE
  

•                                   | 0*SD_BALANCE_EXEC
  

•                                   | 0*SD_BALANCE_FORK
  

•                                   | 1*SD_BALANCE_EXEC
  

•                                   | 1*SD_BALANCE_FORK
                                    | 0*SD_BALANCE_WAKE
  

•                                   | 0*SD_WAKE_AFFINE
  

•                                   | 1*SD_WAKE_AFFINE
                                    | 0*SD_SHARE_CPUPOWER
                                    | 0*SD_SHARE_PKG_RESOURCES
  

•                                   | 1*SD_SERIALIZE
  

•                                   | 0*SD_SERIALIZE
                                    | 0*SD_PREFER_SIBLING
  

•                                   | 1*SD_NUMA
  

•                                   | sd_local_flags(level)
  

•                                   | 0*SD_NUMA
  

•                                   | sd_flags
                                    ,
  

•           .last_balance           = jiffies,
            .balance_interval       = sd_weight,
  

•           .smt_gain               = 0,
  

•           .max_newidle_lb_cost    = 0,
  

•           .next_decay_max_lb_cost = jiffies,
  

+#ifdef CONFIG_SCHED_DEBUG

•           .name                   = tl->name,
  

+#endif };

•   SD_INIT_NAME(sd, NUMA);
  

•   sd->private = &tl->data;
  
    /*
  

•    * Ugly hack to pass state to sd_numa_mask()...
  

•    * Convert topological properties into behaviour.
     */
  

•   sched_domains_curr_level = tl->numa_level;
  

•   if (sd->flags & SD_SHARE_CPUPOWER) {
  

•           sd->imbalance_pct = 110;
  

•           sd->smt_gain = 1178; /* ~15% */
  

•           sd->flags |= arch_sd_sibling_asym_packing();
  

•   } else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
  

•           sd->imbalance_pct = 117;
  

•           sd->cache_nice_tries = 1;
  

•           sd->busy_idx = 2;
  

+#ifdef CONFIG_NUMA

•   } else if (sd->flags & SD_NUMA) {
  

•           sd->cache_nice_tries = 2;
  

•           sd->busy_idx = 3;
  

•           sd->idle_idx = 2;
  

•           sd->flags |= SD_SERIALIZE;
  

•           if (sched_domains_numa_distance[tl->numa_level] > RECLAIM_DISTANCE) {
  

•                   sd->flags &= ~(SD_BALANCE_EXEC |
  

•                                  SD_BALANCE_FORK |
  

•                                  SD_WAKE_AFFINE);
  

•           }
  

+#endif

•   } else {
  

•           sd->flags |= SD_PREFER_SIBLING;
  

•           sd->cache_nice_tries = 1;
  

•           sd->busy_idx = 2;
  

•           sd->idle_idx = 1;
  

•   }
  

This 'if ... else statement' is still a weak point from the perspective of making the code robust:

On TC2 w/ the following change in cpu_corepower_mask()

const struct cpumask *cpu_corepower_mask(int cpu) { - return &cpu_topology[cpu].thread_sibling; + return cpu_topology[cpu].socket_id ? &cpu_topology[cpu].thread_sibling : + &cpu_topology[cpu].core_sibling; }

I get a sane set-up:

root@linaro-developer:~# cat /proc/sys/kernel/sched_domain/cpu*/domain*/name GMC DIE GMC DIE MC DIE MC DIE MC DIE root@linaro-developer:~# cat /proc/sys/kernel/sched_domain/cpu*/domain*/flags 815 4143 815 4143 559 4143 559 4143 559 4143

w/ 815 (0x32F : SD_LOAD_BALANCE SD_BALANCE_NEWIDLE SD_BALANCE_EXEC SD_BALANCE_FORK SD_WAKE_AFFINE *SD_SHARE_POWERDOMAIN* SD_SHARE_PKG_RESOURCES)

w/ 559 (0x22F : SD_LOAD_BALANCE SD_BALANCE_NEWIDLE SD_BALANCE_EXEC SD_BALANCE_FORK SD_WAKE_AFFINE SD_SHARE_PKG_RESOURCES)

But when I introduce the following error into the arch specific cpu_corepower_flags() function

static inline const int cpu_corepower_flags(void) { - return SD_SHARE_PKG_RESOURCES | SD_SHARE_POWERDOMAIN; + return SD_SHARE_POWERDOMAIN; }

the GMC related sd's for CPU0,1 are initialized as DIE in sd_init() resulting in this wrong set-up w/o any warning/error message:

root@linaro-developer:~# cat /proc/sys/kernel/sched_domain/cpu*/domain*/name GMC DIE GMC DIE MC DIE MC DIE MC DIE root@linaro-developer:~# cat /proc/sys/kernel/sched_domain/cpu*/domain*/flags 4399 4143 4399 4143 559 4143 559 4143 559 4143

w/ 4399 (0x112f : SD_LOAD_BALANCE SD_BALANCE_NEWIDLE SD_BALANCE_EXEC SD_BALANCE_FORK SD_WAKE_AFFINE *SD_SHARE_POWERDOMAIN* SD_PREFER_SIBLING

Is there a way to check that MC and GMC have to have SD_SHARE_PKG_RESOURCES set so that this can't happen unnoticed?

-- Dietmar

•   sd->private = &tl->data;
  
    return sd;
  

}

+/*

• • Topology list, bottom-up.
• */

+static struct sched_domain_topology_level default_topology[] = { +#ifdef CONFIG_SCHED_SMT

•   { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
  

+#endif +#ifdef CONFIG_SCHED_MC

•   { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
  

+#endif +#ifdef CONFIG_SCHED_BOOK

•   { cpu_book_mask, SD_INIT_NAME(BOOK) },
  

+#endif

•   { cpu_cpu_mask, SD_INIT_NAME(DIE) },
  

•   { NULL, },
  

+};

+struct sched_domain_topology_level *sched_domain_topology = default_topology;

+#define for_each_sd_topology(tl) \

•   for (tl = sched_domain_topology; tl->mask; tl++)
  

+void set_sched_topology(struct sched_domain_topology_level *tl) +{

•   sched_domain_topology = tl;
  

+}

+#ifdef CONFIG_NUMA

static const struct cpumask *sd_numa_mask(int cpu) { return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)]; @@ -6218,7 +6223,10 @@ static void sched_init_numa(void) } }

•   tl = kzalloc((ARRAY_SIZE(default_topology) + level) *
  

•   /* Compute default topology size */
  

•   for (i = 0; sched_domain_topology[i].mask; i++);
  

•   tl = kzalloc((i + level) *
                    sizeof(struct sched_domain_topology_level), GFP_KERNEL);
    if (!tl)
            return;
  

@@ -6226,18 +6234,19 @@ static void sched_init_numa(void) /* * Copy the default topology bits.. */

•   for (i = 0; default_topology[i].init; i++)
  

•           tl[i] = default_topology[i];
  

•   for (i = 0; sched_domain_topology[i].mask; i++)
  

•           tl[i] = sched_domain_topology[i];
  
    /*
     * .. and append 'j' levels of NUMA goodness.
     */
    for (j = 0; j < level; i++, j++) {
            tl[i] = (struct sched_domain_topology_level){
  

•                   .init = sd_numa_init,
                    .mask = sd_numa_mask,
  

•                   .sd_flags = SD_NUMA,
                    .flags = SDTL_OVERLAP,
                    .numa_level = j,
  

•                   SD_INIT_NAME(NUMA)
            };
    }
  
  

@@ -6395,7 +6404,7 @@ struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl, const struct cpumask *cpu_map, struct sched_domain_attr *attr, struct sched_domain *child, int cpu) {

•   struct sched_domain *sd = tl->init(tl, cpu);
  

•   struct sched_domain *sd = sd_init(tl, cpu);
    if (!sd)
            return child;
  
  

-- 1.9.0

On 03/18/2014 11:26 PM, Vincent Guittot wrote:

Create a dedicated topology table for handling asymetric feature of powerpc.

Signed-off-by: Vincent Guittot vincent.guittot@linaro.org

arch/powerpc/kernel/smp.c | 31 +++++++++++++++++++++++-------- include/linux/sched.h | 2 -- kernel/sched/core.c | 6 ------ 3 files changed, 23 insertions(+), 16 deletions(-)

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index ac2621a..c9cade5 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -755,6 +755,28 @@ int setup_profiling_timer(unsigned int multiplier) return 0; }

+#ifdef CONFIG_SCHED_SMT +/* cpumask of CPUs with asymetric SMT dependancy */ +static const int powerpc_smt_flags(void) +{

• int flags = SD_SHARE_CPUPOWER | SD_SHARE_PKG_RESOURCES;
• if (cpu_has_feature(CPU_FTR_ASYM_SMT)) {

• printk_once(KERN_INFO "Enabling Asymmetric SMT scheduling\n");
  

• flags |= SD_ASYM_PACKING;
  

• }
• return flags;

+} +#endif

+static struct sched_domain_topology_level powerpc_topology[] = { +#ifdef CONFIG_SCHED_SMT

• { cpu_smt_mask, powerpc_smt_flags, SD_INIT_NAME(SMT) },

+#endif

• { cpu_cpu_mask, SD_INIT_NAME(DIE) },
• { NULL, },

+};

void __init smp_cpus_done(unsigned int max_cpus) { cpumask_var_t old_mask; @@ -779,15 +801,8 @@ void __init smp_cpus_done(unsigned int max_cpus)

dump_numa_cpu_topology();

-}

• set_sched_topology(powerpc_topology);

-int arch_sd_sibling_asym_packing(void) -{

• if (cpu_has_feature(CPU_FTR_ASYM_SMT)) {

• printk_once(KERN_INFO "Enabling Asymmetric SMT scheduling\n");
  

• return SD_ASYM_PACKING;
  

• }
• return 0;

}

#ifdef CONFIG_HOTPLUG_CPU diff --git a/include/linux/sched.h b/include/linux/sched.h index 4db592a..6479de4 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -868,8 +868,6 @@ enum cpu_idle_type { #define SD_OVERLAP 0x2000 /* sched_domains of this level overlap */ #define SD_NUMA 0x4000 /* cross-node balancing */

-extern int __weak arch_sd_sibiling_asym_packing(void);

#ifdef CONFIG_SCHED_SMT static inline const int cpu_smt_flags(void) { diff --git a/kernel/sched/core.c b/kernel/sched/core.c index f2bfa76..0b51ee3 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5833,11 +5833,6 @@ static void init_sched_groups_power(int cpu, struct sched_domain *sd) atomic_set(&sg->sgp->nr_busy_cpus, sg->group_weight); }

-int __weak arch_sd_sibling_asym_packing(void) -{

•   return 0*SD_ASYM_PACKING;
  

-}

/*

• Initializers for schedule domains
• Non-inlined to reduce accumulated stack pressure in build_sched_domains()

@@ -6018,7 +6013,6 @@ sd_init(struct sched_domain_topology_level *tl, int cpu) if (sd->flags & SD_SHARE_CPUPOWER) { sd->imbalance_pct = 110; sd->smt_gain = 1178; /* ~15% */

• sd->flags |= arch_sd_sibling_asym_packing();
  
  

  } else if (sd->flags & SD_SHARE_PKG_RESOURCES) { sd->imbalance_pct = 117;

Reviewed-by: Preeti U Murthy preeti@linux.vnet.ibm.com

Hi Vincent,

On 03/18/2014 11:26 PM, Vincent Guittot wrote:

A new flag SD_SHARE_POWERDOMAIN is created to reflect whether groups of CPUs in a sched_domain level can or not reach different power state. As an example, the flag should be cleared at CPU level if groups of cores can be power gated independently. This information can be used to add load balancing level between group of CPUs than can power gate independantly. The default behavior of the scheduler is to spread tasks across CPUs and groups of CPUs so the flag is set into all sched_domains.

I don't see this flag being set either in sd_init() or in default_topology[]. Should not the default_topology[] flag setting routines set this flag at every level of sched domain along with other topology flags, unless the arch wants to override it?

Regards Preeti U Murthy

This flag is part of the topology flags that can be set by arch.

Signed-off-by: Vincent Guittot vincent.guittot@linaro.org

include/linux/sched.h | 1 + kernel/sched/core.c | 9 ++++++--- 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h index 6479de4..7048369 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -861,6 +861,7 @@ enum cpu_idle_type { #define SD_BALANCE_WAKE 0x0010 /* Balance on wakeup */ #define SD_WAKE_AFFINE 0x0020 /* Wake task to waking CPU */ #define SD_SHARE_CPUPOWER 0x0080 /* Domain members share cpu power */ +#define SD_SHARE_POWERDOMAIN 0x0100 /* Domain members share power domain */ #define SD_SHARE_PKG_RESOURCES 0x0200 /* Domain members share cpu pkg resources */ #define SD_SERIALIZE 0x0400 /* Only a single load balancing instance */ #define SD_ASYM_PACKING 0x0800 /* Place busy groups earlier in the domain */ diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 0b51ee3..224ec3b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5298,7 +5298,8 @@ static int sd_degenerate(struct sched_domain *sd) SD_BALANCE_FORK | SD_BALANCE_EXEC | SD_SHARE_CPUPOWER |

• 	 SD_SHARE_PKG_RESOURCES)) {
  

• 	 SD_SHARE_PKG_RESOURCES |
  

• 	 SD_SHARE_POWERDOMAIN)) {
  

  if (sd->groups != sd->groups->next) return 0; }

@@ -5329,7 +5330,8 @@ sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent) SD_BALANCE_EXEC | SD_SHARE_CPUPOWER | SD_SHARE_PKG_RESOURCES |

• 		SD_PREFER_SIBLING);
  

• 		SD_PREFER_SIBLING |
  

• 		SD_SHARE_POWERDOMAIN);
  

  if (nr_node_ids == 1) pflags &= ~SD_SERIALIZE; }

@@ -5946,7 +5948,8 @@ static int sched_domains_curr_level; (SD_SHARE_CPUPOWER | \ SD_SHARE_PKG_RESOURCES | \ SD_NUMA | \

• SD_ASYM_PACKING)
  

• SD_ASYM_PACKING |		\
  

• SD_SHARE_POWERDOMAIN)
  
  

static struct sched_domain * sd_init(struct sched_domain_topology_level *tl, int cpu)

On 03/19/2014 03:22 PM, Vincent Guittot wrote:

On 19 March 2014 07:21, Preeti U Murthy preeti@linux.vnet.ibm.com wrote:

...

Hi Vincent,

On 03/18/2014 11:26 PM, Vincent Guittot wrote:

...

A new flag SD_SHARE_POWERDOMAIN is created to reflect whether groups of CPUs in a sched_domain level can or not reach different power state. As an example, the flag should be cleared at CPU level if groups of cores can be power gated independently. This information can be used to add load balancing level between group of CPUs than can power gate independantly. The default behavior of the scheduler is to spread tasks across CPUs and groups of CPUs so the flag is set into all sched_domains.

I don't see this flag being set either in sd_init() or in default_topology[]. Should not the default_topology[] flag setting routines set this flag at every level of sched domain along with other topology flags, unless the arch wants to override it?

Hi Preeti

I have made the choice to not add it in the default table for the moment because the scheduler behavior is not changed. It will be added with patchset that will take advantage of this flag in the load balance decision.

Ok if you are looking at setting this flag in the default topology table then [patch 7/7]:sched: powerpc: Add SD_SHARE_POWERDOMAIN for SMT level looks good to me. Please add my Reviewed-by to this patch.

However if you are looking at initializing this flag as being set by default in sd_init() then the archs will have to revert the flag, rather than set it in their respective topology tables for the sched domains which have their groups power gated. In which case the [patch 7/7] would be incorrect. But wait, I see that you mention that the topology level flags are left to the archs to set if required. So I am assuming you will not set the SD_SHARE_POWER_DOMAIN flag in sd_init() right?

Regards Preeti U Murthy

Regards, Vincent

...

Regards Preeti U Murthy

...

This flag is part of the topology flags that can be set by arch.

Signed-off-by: Vincent Guittot vincent.guittot@linaro.org

include/linux/sched.h | 1 + kernel/sched/core.c | 9 ++++++--- 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h index 6479de4..7048369 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -861,6 +861,7 @@ enum cpu_idle_type { #define SD_BALANCE_WAKE 0x0010 /* Balance on wakeup */ #define SD_WAKE_AFFINE 0x0020 /* Wake task to waking CPU */ #define SD_SHARE_CPUPOWER 0x0080 /* Domain members share cpu power */ +#define SD_SHARE_POWERDOMAIN 0x0100 /* Domain members share power domain */ #define SD_SHARE_PKG_RESOURCES 0x0200 /* Domain members share cpu pkg resources */ #define SD_SERIALIZE 0x0400 /* Only a single load balancing instance */ #define SD_ASYM_PACKING 0x0800 /* Place busy groups earlier in the domain */ diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 0b51ee3..224ec3b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5298,7 +5298,8 @@ static int sd_degenerate(struct sched_domain *sd) SD_BALANCE_FORK | SD_BALANCE_EXEC | SD_SHARE_CPUPOWER |

•                  SD_SHARE_PKG_RESOURCES)) {
  

•                  SD_SHARE_PKG_RESOURCES |
  

•                  SD_SHARE_POWERDOMAIN)) {
          if (sd->groups != sd->groups->next)
                  return 0;
  }
  

@@ -5329,7 +5330,8 @@ sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent) SD_BALANCE_EXEC | SD_SHARE_CPUPOWER | SD_SHARE_PKG_RESOURCES |

•                         SD_PREFER_SIBLING);
  

•                         SD_PREFER_SIBLING |
  

•                         SD_SHARE_POWERDOMAIN);
          if (nr_node_ids == 1)
                  pflags &= ~SD_SERIALIZE;
  }
  

@@ -5946,7 +5948,8 @@ static int sched_domains_curr_level; (SD_SHARE_CPUPOWER | \ SD_SHARE_PKG_RESOURCES | \ SD_NUMA | \

•  SD_ASYM_PACKING)
  

•  SD_ASYM_PACKING |              \
  

•  SD_SHARE_POWERDOMAIN)
  
  

static struct sched_domain * sd_init(struct sched_domain_topology_level *tl, int cpu)

On Tue, Mar 18, 2014 at 06:56:47PM +0100, Vincent Guittot wrote:

@@ -5946,7 +5948,8 @@ static int sched_domains_curr_level; (SD_SHARE_CPUPOWER | \ SD_SHARE_PKG_RESOURCES | \ SD_NUMA | \

• SD_ASYM_PACKING)
  

• SD_ASYM_PACKING |		\
  

• SD_SHARE_POWERDOMAIN)
  

You forgot to update the pretty comment above that :-)