On Tuesday 08 October 2002 08:08, Martin J. Bligh wrote:
> I did:
>
> 1. remove asm/numa.h declaration (you need to work out something
> generic here ... mmzone.h should include it, I think?)
> 2. changed NR_NODES to MAX_NUMNODES everywhere.
> 3. Put in an extern declartion into fs/exec.c for sched_balance_exec
>
> Then I got bored around the linking problem. Does this compile for
> you somehow?
Aaargh, you got the wrong second patch :-( Sorry for that...
Thanks for the hints, I cleaned up the first patch, too. No
CONFIG_NUMA_SCHED any more, switched to MAX_NUMNODES, including
asm/numa.h from asm/topology.h, so no need for you to see it.
Erich
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diff -urNp a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c
--- a/arch/i386/kernel/smpboot.c Fri Sep 27 23:49:54 2002
+++ b/arch/i386/kernel/smpboot.c Tue Oct 8 11:37:56 2002
@@ -1194,6 +1194,11 @@ int __devinit __cpu_up(unsigned int cpu)
void __init smp_cpus_done(unsigned int max_cpus)
{
zap_low_mappings();
+#ifdef CONFIG_NUMA
+ pooldata_lock();
+ bld_pools();
+ pooldata_unlock();
+#endif
}
void __init smp_intr_init()
diff -urNp a/arch/ia64/kernel/smpboot.c b/arch/ia64/kernel/smpboot.c
--- a/arch/ia64/kernel/smpboot.c Tue Oct 8 10:57:10 2002
+++ b/arch/ia64/kernel/smpboot.c Tue Oct 8 11:38:17 2002
@@ -397,7 +397,7 @@ unsigned long cache_decay_ticks; /* # of
static void
smp_tune_scheduling (void)
{
- cache_decay_ticks = 10; /* XXX base this on PAL info and cache-bandwidth estimate */
+ cache_decay_ticks = 8; /* XXX base this on PAL info and cache-bandwidth estimate */
printk("task migration cache decay timeout: %ld msecs.\n",
(cache_decay_ticks + 1) * 1000 / HZ);
@@ -508,6 +508,11 @@ smp_cpus_done (unsigned int dummy)
printk(KERN_INFO"Total of %d processors activated (%lu.%02lu BogoMIPS).\n",
num_online_cpus(), bogosum/(500000/HZ), (bogosum/(5000/HZ))%100);
+#ifdef CONFIG_NUMA
+ pooldata_lock();
+ bld_pools();
+ pooldata_unlock();
+#endif
}
int __devinit
diff -urNp a/include/asm-i386/atomic.h b/include/asm-i386/atomic.h
--- a/include/asm-i386/atomic.h Fri Sep 27 23:49:16 2002
+++ b/include/asm-i386/atomic.h Tue Oct 8 10:59:13 2002
@@ -111,6 +111,18 @@ static __inline__ void atomic_inc(atomic
}
/**
+ * atomic_inc_return - increment atomic variable and return new value
+ * @v: pointer of type atomic_t
+ *
+ * Atomically increments @v by 1 and return it's new value. Note that
+ * the guaranteed useful range of an atomic_t is only 24 bits.
+ */
+static inline int atomic_inc_return(atomic_t *v){
+ atomic_inc(v);
+ return v->counter;
+}
+
+/**
* atomic_dec - decrement atomic variable
* @v: pointer of type atomic_t
*
diff -urNp a/include/linux/sched.h b/include/linux/sched.h
--- a/include/linux/sched.h Tue Oct 8 10:56:28 2002
+++ b/include/linux/sched.h Tue Oct 8 11:30:21 2002
@@ -22,6 +22,7 @@ extern unsigned long event;
#include <asm/mmu.h>
#include <linux/smp.h>
+#include <asm/topology.h>
#include <linux/sem.h>
#include <linux/signal.h>
#include <linux/securebits.h>
@@ -167,7 +168,6 @@ extern void update_one_process(struct ta
extern void scheduler_tick(int user_tick, int system);
extern unsigned long cache_decay_ticks;
-
#define MAX_SCHEDULE_TIMEOUT LONG_MAX
extern signed long FASTCALL(schedule_timeout(signed long timeout));
asmlinkage void schedule(void);
@@ -457,6 +457,12 @@ extern void set_cpus_allowed(task_t *p,
# define set_cpus_allowed(p, new_mask) do { } while (0)
#endif
+#ifdef CONFIG_NUMA
+extern void pooldata_lock(void);
+extern void pooldata_unlock(void);
+#endif
+extern void sched_migrate_task(task_t *p, int cpu);
+
extern void set_user_nice(task_t *p, long nice);
extern int task_prio(task_t *p);
extern int task_nice(task_t *p);
diff -urNp a/kernel/sched.c b/kernel/sched.c
--- a/kernel/sched.c Fri Sep 27 23:50:27 2002
+++ b/kernel/sched.c Tue Oct 8 11:19:40 2002
@@ -154,6 +154,10 @@ struct runqueue {
task_t *migration_thread;
struct list_head migration_queue;
+ unsigned long wait_time;
+ int wait_node;
+ int load[2][NR_CPUS];
+
} ____cacheline_aligned;
static struct runqueue runqueues[NR_CPUS] __cacheline_aligned;
@@ -174,6 +178,95 @@ static struct runqueue runqueues[NR_CPUS
#endif
/*
+ * Variables for describing and accessing processor pools. Using a
+ * compressed row format like notation. Processor pools are treated
+ * like logical node numbers.
+ *
+ * numpools: number of CPU pools (nodes),
+ * pool_cpus[]: CPUs in pools sorted by their pool ID,
+ * pool_ptr[pool]: index of first element in pool_cpus[] belonging to pool.
+ * pool_mask[]: cpu mask of a pool.
+ *
+ * Example: loop over all CPUs in a pool p:
+ * loop_over_node(i,node) {
+ * cpu = pool_cpu(i);
+ * ...
+ * }
+ * <efocht@ess.nec.de>
+ */
+int numpools, pool_ptr[MAX_NUMNODES+1], pool_cpus[NR_CPUS], pool_nr_cpus[MAX_NUMNODES];
+unsigned long pool_mask[MAX_NUMNODES];
+static atomic_t pool_lock = ATOMIC_INIT(0);
+#define cpu_to_node(cpu) __cpu_to_node(cpu)
+
+/* Avoid zeroes in integer divides for load calculations */
+#define BALANCE_FACTOR 100
+
+#ifdef CONFIG_NUMA
+#define POOL_DELAY (100)
+#define loop_over_node(i,n) for(i=pool_ptr[n]; i<pool_ptr[n+1]; i++)
+#define pool_cpu(i) pool_cpus[i]
+
+void pooldata_lock(void)
+{
+ int i;
+ retry:
+ while (atomic_read(&pool_lock));
+ if (atomic_inc_return(&pool_lock) > 1) {
+ atomic_dec(&pool_lock);
+ goto retry;
+ }
+ /*
+ * Wait a while, any loops using pool data should finish
+ * in between. This is VERY ugly and should be replaced
+ * by some real RCU stuff. [EF]
+ */
+ for (i=0; i<100; i++)
+ udelay(1000);
+}
+
+void pooldata_unlock(void)
+{
+ atomic_dec(&pool_lock);
+}
+
+/*
+ * Call pooldata_lock() before calling this function and
+ * pooldata_unlock() after!
+ */
+void bld_pools(void)
+{
+ int n, cpu, ptr, i;
+ unsigned long mask;
+
+ ptr=0;
+ for (n=0; n<numnodes; n++) {
+ mask = pool_mask[n] = __node_to_cpu_mask(n) & cpu_online_map;
+ pool_ptr[n] = ptr;
+ for (cpu=0; cpu<NR_CPUS; cpu++)
+ if (mask & (1UL << cpu))
+ pool_cpu(ptr++) = cpu;
+ pool_nr_cpus[n] = ptr - pool_ptr[n];
+ }
+ numpools=numnodes;
+ pool_ptr[numpools]=ptr;
+ printk("CPU pools : %d\n",numpools);
+ for (n=0;n<numpools;n++) {
+ printk("pool %d :",n);
+ loop_over_node(i,n)
+ printk("%d ",pool_cpu(i));
+ printk("\n");
+ }
+}
+
+#else
+#define POOL_DELAY (0)
+#define loop_over_node(i,n) for(i=0; i<NR_CPUS; i++)
+#define pool_cpu(i) (i)
+#endif
+
+
+/*
* task_rq_lock - lock the runqueue a given task resides on and disable
* interrupts. Note the ordering: we can safely lookup the task_rq without
* explicitly disabling preemption.
@@ -632,121 +725,144 @@ static inline unsigned int double_lock_b
}
/*
- * find_busiest_queue - find the busiest runqueue.
+ * Calculate load of a CPU pool, store results in data[][NR_CPUS].
+ * Return the index of the most loaded runqueue.
*/
-static inline runqueue_t *find_busiest_queue(runqueue_t *this_rq, int this_cpu, int idle, int *imbalance)
+static int calc_pool_load(int data[][NR_CPUS], int this_cpu, int pool, int idle)
{
- int nr_running, load, max_load, i;
- runqueue_t *busiest, *rq_src;
-
- /*
- * We search all runqueues to find the most busy one.
- * We do this lockless to reduce cache-bouncing overhead,
- * we re-check the 'best' source CPU later on again, with
- * the lock held.
- *
- * We fend off statistical fluctuations in runqueue lengths by
- * saving the runqueue length during the previous load-balancing
- * operation and using the smaller one the current and saved lengths.
- * If a runqueue is long enough for a longer amount of time then
- * we recognize it and pull tasks from it.
- *
- * The 'current runqueue length' is a statistical maximum variable,
- * for that one we take the longer one - to avoid fluctuations in
- * the other direction. So for a load-balance to happen it needs
- * stable long runqueue on the target CPU and stable short runqueue
- * on the local runqueue.
- *
- * We make an exception if this CPU is about to become idle - in
- * that case we are less picky about moving a task across CPUs and
- * take what can be taken.
- */
- if (idle || (this_rq->nr_running > this_rq->prev_nr_running[this_cpu]))
- nr_running = this_rq->nr_running;
- else
- nr_running = this_rq->prev_nr_running[this_cpu];
+ runqueue_t *rq_src, *this_rq = cpu_rq(this_cpu);
+ int i, ii, idx=-1, refload, load;
- busiest = NULL;
- max_load = 1;
- for (i = 0; i < NR_CPUS; i++) {
- if (!cpu_online(i))
- continue;
+ data[1][pool] = 0;
+ refload = -1;
+ loop_over_node(ii, pool) {
+ i = pool_cpu(ii);
rq_src = cpu_rq(i);
if (idle || (rq_src->nr_running < this_rq->prev_nr_running[i]))
load = rq_src->nr_running;
else
load = this_rq->prev_nr_running[i];
this_rq->prev_nr_running[i] = rq_src->nr_running;
-
- if ((load > max_load) && (rq_src != this_rq)) {
- busiest = rq_src;
- max_load = load;
+ data[0][i] = load;
+ data[1][pool] += load;
+ if (load > refload) {
+ idx = i;
+ refload = load;
}
}
+ data[1][pool] = data[1][pool] * BALANCE_FACTOR / pool_nr_cpus[pool];
+ return idx;
+}
- if (likely(!busiest))
- goto out;
+/*
+ * Find a runqueue from which to steal a task. We try to do this as locally as
+ * possible because we don't want to let tasks get far from their home node.
+ * This is done in two steps:
+ * 1. First try to find a runqueue within the own CPU pool (AKA node) with
+ * imbalance larger than 25% (relative to the current runqueue).
+ * 2. If the local node is well balanced, locate the most loaded node and its
+ * most loaded CPU. Remote runqueues running tasks having their homenode on the
+ * current node are preferred (those tasks count twice in the load calculation).
+ * If the current load is far below the average try to steal a task from the
+ * most loaded node/cpu. Otherwise wait 100ms and give less loaded nodes the
+ * chance to approach the average load.
+ *
+ * This concept can be extended easilly to more than two levels (multi-level
+ * scheduler?), e.g.: CPU -> multi-core package -> node -> supernode...
+ * <efocht@ess.nec.de>
+ */
+static inline runqueue_t *find_busiest_queue(runqueue_t *this_rq, int this_cpu,
+ int idle, int *nr_running)
+{
+ runqueue_t *busiest = NULL;
+ int imax, best_cpu, pool, max_pool_load, max_pool_idx;
+ int i, del_shift;
+ int avg_load=-1, this_pool = cpu_to_node(this_cpu);
+
+ /* Need at least ~25% imbalance to trigger balancing. */
+#define BALANCED(m,t) (((m) <= 1) || (((m) - (t))/2 < (((m) + (t))/2 + 3)/4))
+
+ if (idle || (this_rq->nr_running > this_rq->prev_nr_running[this_cpu]))
+ *nr_running = this_rq->nr_running;
+ else
+ *nr_running = this_rq->prev_nr_running[this_cpu];
- *imbalance = (max_load - nr_running) / 2;
+ best_cpu = calc_pool_load(this_rq->load, this_cpu, this_pool, idle);
+
+ if (best_cpu != this_cpu)
+ goto check_out;
- /* It needs an at least ~25% imbalance to trigger balancing. */
- if (!idle && (*imbalance < (max_load + 3)/4)) {
- busiest = NULL;
+ scan_all:
+ best_cpu = -1;
+ max_pool_load = this_rq->load[1][this_pool];
+ max_pool_idx = this_pool;
+ avg_load = max_pool_load * pool_nr_cpus[this_pool];
+ for (i = 1; i < numpools; i++) {
+ pool = (i + this_pool) % numpools;
+ imax = calc_pool_load(this_rq->load, this_cpu, pool, idle);
+ avg_load += this_rq->load[1][pool]*pool_nr_cpus[pool];
+ if (this_rq->load[1][pool] > max_pool_load) {
+ max_pool_load = this_rq->load[1][pool];
+ max_pool_idx = pool;
+ best_cpu = imax;
+ }
+ }
+ /* Exit if not enough imbalance on any remote node. */
+ if ((best_cpu < 0) ||
+ BALANCED(max_pool_load,this_rq->load[1][this_pool])) {
+ this_rq->wait_node = -1;
goto out;
}
+ avg_load /= num_online_cpus();
+ /* Wait longer before stealing if load is average. */
+ if (BALANCED(avg_load,this_rq->load[1][this_pool]))
+ del_shift = 0;
+ else
+ del_shift = 6;
- nr_running = double_lock_balance(this_rq, busiest, this_cpu, idle, nr_running);
- /*
- * Make sure nothing changed since we checked the
- * runqueue length.
- */
- if (busiest->nr_running <= nr_running + 1) {
- spin_unlock(&busiest->lock);
- busiest = NULL;
- }
-out:
+ if (this_rq->wait_node != max_pool_idx) {
+ this_rq->wait_node = max_pool_idx;
+ this_rq->wait_time = jiffies;
+ goto out;
+ } else
+ if (jiffies - this_rq->wait_time < (POOL_DELAY >> del_shift))
+ goto out;
+
+ check_out:
+ /* Enough imbalance in the remote cpu loads? */
+ if (!BALANCED(this_rq->load[0][best_cpu],*nr_running)) {
+ busiest = cpu_rq(best_cpu);
+ this_rq->wait_node = -1;
+ } else if (avg_load == -1)
+ /* only scanned local pool, so let's look at all of them */
+ goto scan_all;
+ out:
return busiest;
}
/*
- * pull_task - move a task from a remote runqueue to the local runqueue.
- * Both runqueues must be locked.
+ * Find a task to steal from the busiest RQ. The busiest->lock must be held
+ * while calling this routine.
*/
-static inline void pull_task(runqueue_t *src_rq, prio_array_t *src_array, task_t *p, runqueue_t *this_rq, int this_cpu)
+static inline task_t *task_to_steal(runqueue_t *busiest, int this_cpu)
{
- dequeue_task(p, src_array);
- src_rq->nr_running--;
- set_task_cpu(p, this_cpu);
- this_rq->nr_running++;
- enqueue_task(p, this_rq->active);
- /*
- * Note that idle threads have a prio of MAX_PRIO, for this test
- * to be always true for them.
- */
- if (p->prio < this_rq->curr->prio)
- set_need_resched();
-}
-
-/*
- * Current runqueue is empty, or rebalance tick: if there is an
- * inbalance (current runqueue is too short) then pull from
- * busiest runqueue(s).
- *
- * We call this with the current runqueue locked,
- * irqs disabled.
- */
-static void load_balance(runqueue_t *this_rq, int idle)
-{
- int imbalance, idx, this_cpu = smp_processor_id();
- runqueue_t *busiest;
+ int idx;
+ task_t *next = NULL, *tmp;
prio_array_t *array;
struct list_head *head, *curr;
- task_t *tmp;
+ int weight, maxweight=0;
- busiest = find_busiest_queue(this_rq, this_cpu, idle, &imbalance);
- if (!busiest)
- goto out;
+ /*
+ * We do not migrate tasks that are:
+ * 1) running (obviously), or
+ * 2) cannot be migrated to this CPU due to cpus_allowed.
+ */
+
+#define CAN_MIGRATE_TASK(p,rq,this_cpu) \
+ ((jiffies - (p)->sleep_timestamp > cache_decay_ticks) && \
+ p != rq->curr && \
+ ((p)->cpus_allowed & (1UL<<(this_cpu))))
/*
* We first consider expired tasks. Those will likely not be
@@ -772,7 +888,7 @@ skip_bitmap:
array = busiest->active;
goto new_array;
}
- goto out_unlock;
+ goto out;
}
head = array->queue + idx;
@@ -780,33 +896,74 @@ skip_bitmap:
skip_queue:
tmp = list_entry(curr, task_t, run_list);
+ if (CAN_MIGRATE_TASK(tmp, busiest, this_cpu)) {
+ weight = (jiffies - tmp->sleep_timestamp)/cache_decay_ticks;
+ if (weight > maxweight) {
+ maxweight = weight;
+ next = tmp;
+ }
+ }
+ curr = curr->next;
+ if (curr != head)
+ goto skip_queue;
+ idx++;
+ goto skip_bitmap;
+
+ out:
+ return next;
+}
+
+/*
+ * pull_task - move a task from a remote runqueue to the local runqueue.
+ * Both runqueues must be locked.
+ */
+static inline void pull_task(runqueue_t *src_rq, prio_array_t *src_array, task_t *p, runqueue_t *this_rq, int this_cpu)
+{
+ dequeue_task(p, src_array);
+ src_rq->nr_running--;
+ set_task_cpu(p, this_cpu);
+ this_rq->nr_running++;
+ enqueue_task(p, this_rq->active);
/*
- * We do not migrate tasks that are:
- * 1) running (obviously), or
- * 2) cannot be migrated to this CPU due to cpus_allowed, or
- * 3) are cache-hot on their current CPU.
+ * Note that idle threads have a prio of MAX_PRIO, for this test
+ * to be always true for them.
*/
+ if (p->prio < this_rq->curr->prio)
+ set_need_resched();
+}
-#define CAN_MIGRATE_TASK(p,rq,this_cpu) \
- ((jiffies - (p)->sleep_timestamp > cache_decay_ticks) && \
- !task_running(rq, p) && \
- ((p)->cpus_allowed & (1UL << (this_cpu))))
-
- curr = curr->prev;
-
- if (!CAN_MIGRATE_TASK(tmp, busiest, this_cpu)) {
- if (curr != head)
- goto skip_queue;
- idx++;
- goto skip_bitmap;
- }
- pull_task(busiest, array, tmp, this_rq, this_cpu);
- if (!idle && --imbalance) {
- if (curr != head)
- goto skip_queue;
- idx++;
- goto skip_bitmap;
- }
+/*
+ * Current runqueue is empty, or rebalance tick: if there is an
+ * inbalance (current runqueue is too short) then pull from
+ * busiest runqueue(s).
+ *
+ * We call this with the current runqueue locked,
+ * irqs disabled.
+ */
+static void load_balance(runqueue_t *this_rq, int idle)
+{
+ int nr_running, this_cpu = task_cpu(this_rq->curr);
+ task_t *tmp;
+ runqueue_t *busiest;
+
+ /* avoid deadlock by timer interrupt on own cpu */
+ if (atomic_read(&pool_lock)) return;
+ busiest = find_busiest_queue(this_rq, this_cpu, idle, &nr_running);
+ if (!busiest)
+ goto out;
+
+ nr_running = double_lock_balance(this_rq, busiest, this_cpu, idle, nr_running);
+ /*
+ * Make sure nothing changed since we checked the
+ * runqueue length.
+ */
+ if (busiest->nr_running <= nr_running + 1)
+ goto out_unlock;
+
+ tmp = task_to_steal(busiest, this_cpu);
+ if (!tmp)
+ goto out_unlock;
+ pull_task(busiest, tmp->array, tmp, this_rq, this_cpu);
out_unlock:
spin_unlock(&busiest->lock);
out:
@@ -819,10 +976,10 @@ out:
* frequency and balancing agressivity depends on whether the CPU is
* idle or not.
*
- * busy-rebalance every 250 msecs. idle-rebalance every 1 msec. (or on
+ * busy-rebalance every 200 msecs. idle-rebalance every 1 msec. (or on
* systems with HZ=100, every 10 msecs.)
*/
-#define BUSY_REBALANCE_TICK (HZ/4 ?: 1)
+#define BUSY_REBALANCE_TICK (HZ/5 ?: 1)
#define IDLE_REBALANCE_TICK (HZ/1000 ?: 1)
static inline void idle_tick(runqueue_t *rq)
@@ -1920,6 +2077,8 @@ typedef struct {
struct list_head list;
task_t *task;
struct completion done;
+ int cpu_dest;
+ int sync;
} migration_req_t;
/*
@@ -1965,6 +2124,7 @@ void set_cpus_allowed(task_t *p, unsigne
}
init_completion(&req.done);
req.task = p;
+ req.sync = 1;
list_add(&req.list, &rq->migration_queue);
task_rq_unlock(rq, &flags);
wake_up_process(rq->migration_thread);
@@ -1974,6 +2134,17 @@ out:
preempt_enable();
}
+void sched_migrate_task(task_t *p, int dest_cpu)
+{
+ unsigned long old_mask;
+
+ old_mask = p->cpus_allowed;
+ if (!(old_mask & (1UL << dest_cpu)))
+ return;
+ set_cpus_allowed(p, 1UL << dest_cpu);
+ set_cpus_allowed(p, old_mask);
+}
+
/*
* migration_thread - this is a highprio system thread that performs
* thread migration by 'pulling' threads into the target runqueue.
@@ -2009,7 +2180,7 @@ static int migration_thread(void * data)
for (;;) {
runqueue_t *rq_src, *rq_dest;
struct list_head *head;
- int cpu_src, cpu_dest;
+ int cpu_src, cpu_dest, sync;
migration_req_t *req;
unsigned long flags;
task_t *p;
@@ -2024,10 +2195,17 @@ static int migration_thread(void * data)
}
req = list_entry(head->next, migration_req_t, list);
list_del_init(head->next);
- spin_unlock_irqrestore(&rq->lock, flags);
p = req->task;
- cpu_dest = __ffs(p->cpus_allowed);
+ sync = req->sync;
+ if (sync)
+ cpu_dest = __ffs(p->cpus_allowed & cpu_online_map);
+ else {
+ cpu_dest = req->cpu_dest;
+ req->task = NULL;
+ }
+ spin_unlock_irqrestore(&rq->lock, flags);
+
rq_dest = cpu_rq(cpu_dest);
repeat:
cpu_src = task_cpu(p);
@@ -2050,7 +2228,8 @@ repeat:
double_rq_unlock(rq_src, rq_dest);
local_irq_restore(flags);
- complete(&req->done);
+ if (sync)
+ complete(&req->done);
}
}
@@ -2130,6 +2309,15 @@ void __init sched_init(void)
__set_bit(MAX_PRIO, array->bitmap);
}
}
+#ifdef CONFIG_NUMA
+ pool_ptr[0] = 0;
+ pool_ptr[1] = NR_CPUS;
+
+ numpools = 1;
+ pool_mask[0] = -1L;
+ pool_nr_cpus[0] = NR_CPUS;
+#endif
+
/*
* We have to do a little magic to get the first
* thread right in SMP mode.
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name="02-numa_sched_ilb-2.5.39.patch"
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Content-Disposition: attachment; filename="02-numa_sched_ilb-2.5.39.patch"
diff -urNp a/fs/exec.c b/fs/exec.c
--- a/fs/exec.c Tue Oct 8 15:03:54 2002
+++ b/fs/exec.c Tue Oct 8 15:08:22 2002
@@ -993,6 +993,7 @@ int do_execve(char * filename, char ** a
int retval;
int i;
+ sched_balance_exec();
file = open_exec(filename);
retval = PTR_ERR(file);
diff -urNp a/include/linux/sched.h b/include/linux/sched.h
--- a/include/linux/sched.h Tue Oct 8 15:07:48 2002
+++ b/include/linux/sched.h Tue Oct 8 15:09:27 2002
@@ -460,6 +460,9 @@ extern void set_cpus_allowed(task_t *p,
#ifdef CONFIG_NUMA
extern void pooldata_lock(void);
extern void pooldata_unlock(void);
+extern void sched_balance_exec(void);
+#else
+#define sched_balance_exec() {}
#endif
extern void sched_migrate_task(task_t *p, int cpu);
diff -urNp a/kernel/sched.c b/kernel/sched.c
--- a/kernel/sched.c Tue Oct 8 15:07:48 2002
+++ b/kernel/sched.c Tue Oct 8 15:08:22 2002
@@ -2134,6 +2134,78 @@ out:
preempt_enable();
}
+#ifdef CONFIG_NUMA
+/* used as counter for round-robin node-scheduling */
+static atomic_t sched_node=ATOMIC_INIT(0);
+
+/*
+ * Find the least loaded CPU on the current node of the task.
+ */
+static int sched_best_cpu(struct task_struct *p, int node)
+{
+ int n, cpu, load, best_cpu = task_cpu(p);
+
+ load = 1000000;
+ loop_over_node(n,node) {
+ cpu = pool_cpu(n);
+ if (!(p->cpus_allowed & (1UL << cpu) & cpu_online_map))
+ continue;
+ if (cpu_rq(cpu)->nr_running < load) {
+ best_cpu = cpu;
+ load = cpu_rq(cpu)->nr_running;
+ }
+ }
+ return best_cpu;
+}
+
+/*
+ * Find the node with fewest number of tasks running on it.
+ */
+static int sched_best_node(struct task_struct *p)
+{
+ int i, n, best_node=0, min_load, pool_load, min_pool=numa_node_id();
+ int cpu, pool, load;
+ unsigned long mask = p->cpus_allowed & cpu_online_map;
+
+ do {
+ best_node = atomic_inc_return(&sched_node) % numpools;
+ } while (!(pool_mask[best_node] & mask));
+
+ min_load = 100000000;
+ for (n = 0; n < numpools; n++) {
+ pool = (best_node + n) % numpools;
+ load = 0;
+ loop_over_node(i, pool) {
+ cpu=pool_cpu(i);
+ if (!cpu_online(cpu)) continue;
+ load += cpu_rq(cpu)->nr_running;
+ }
+ if (pool == numa_node_id()) load--;
+ pool_load = 100*load/pool_nr_cpus[pool];
+ if ((pool_load < min_load) && (pool_mask[pool] & mask)) {
+ min_load = pool_load;
+ min_pool = pool;
+ }
+ }
+ atomic_set(&sched_node, min_pool);
+ return min_pool;
+}
+
+void sched_balance_exec(void)
+{
+ int new_cpu, new_node=0;
+
+ while (atomic_read(&pool_lock))
+ cpu_relax();
+ if (numpools > 1) {
+ new_node = sched_best_node(current);
+ }
+ new_cpu = sched_best_cpu(current, new_node);
+ if (new_cpu != smp_processor_id())
+ sched_migrate_task(current, new_cpu);
+}
+#endif
+
void sched_migrate_task(task_t *p, int dest_cpu)
{
unsigned long old_mask;
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