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authorChristoph Hellwig <hch@lst.de>2007-02-13 21:54:29 +0100
committerArnd Bergmann <arnd@klappe.arndb.de>2007-02-13 21:55:43 +0100
commit2eb1b12049844a8ebc670e0e4fc908bc3f8933d3 (patch)
treeb02521b88557dddabcb9de649855151323881cc0 /arch/powerpc/platforms/cell/spufs/sched.c
parent72cb360839f88c02ccf38f1df214316e05886ff3 (diff)
[POWERPC] spu sched: static timeslicing for SCHED_RR contexts
For SCHED_RR tasks we can do some really trivial timeslicing. Basically we fire up a time for every scheduler tick that searches for a higher or same priority thread that is on the runqueue and if there is one context switches to it. Because we can't lock spus from timer context we actually run this from a delayed runqueue instead of a timer. A nice optimization would be to skip the actual priority bitmap search when there are less contexts than physical spus available. To implement this I need a so far unpublished patch from Andre, and it will be added after we have that patch in. Note that right now we only do the time slicing for SCHED_RR tasks. The code would work for SCHED_OTHER tasks aswell, but their prio value is defered from the one the PPU thread has at time of spu_run, and using this for spu scheduling decisions would make the code very unfair. SCHED_OTHER support will be enabled once we the spu scheduler knows how to calculcate cpu_context.prio (very soon) Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Diffstat (limited to 'arch/powerpc/platforms/cell/spufs/sched.c')
-rw-r--r--arch/powerpc/platforms/cell/spufs/sched.c43
1 files changed, 42 insertions, 1 deletions
diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index ba4b01e01ace..2f25e68b4bac 100644
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -44,7 +44,7 @@
#include <asm/spu_priv1.h>
#include "spufs.h"
-#define SPU_MIN_TIMESLICE (100 * HZ / 1000)
+#define SPU_TIMESLICE (HZ)
struct spu_prio_array {
DECLARE_BITMAP(bitmap, MAX_PRIO);
@@ -55,6 +55,7 @@ struct spu_prio_array {
};
static struct spu_prio_array *spu_prio;
+static struct workqueue_struct *spu_sched_wq;
static inline int node_allowed(int node)
{
@@ -68,6 +69,40 @@ static inline int node_allowed(int node)
return 1;
}
+void spu_start_tick(struct spu_context *ctx)
+{
+ if (ctx->policy == SCHED_RR)
+ queue_delayed_work(spu_sched_wq, &ctx->sched_work, SPU_TIMESLICE);
+}
+
+void spu_stop_tick(struct spu_context *ctx)
+{
+ if (ctx->policy == SCHED_RR)
+ cancel_delayed_work(&ctx->sched_work);
+}
+
+void spu_sched_tick(struct work_struct *work)
+{
+ struct spu_context *ctx =
+ container_of(work, struct spu_context, sched_work.work);
+ struct spu *spu;
+ int rearm = 1;
+
+ mutex_lock(&ctx->state_mutex);
+ spu = ctx->spu;
+ if (spu) {
+ int best = sched_find_first_bit(spu_prio->bitmap);
+ if (best <= ctx->prio) {
+ spu_deactivate(ctx);
+ rearm = 0;
+ }
+ }
+ mutex_unlock(&ctx->state_mutex);
+
+ if (rearm)
+ spu_start_tick(ctx);
+}
+
/**
* spu_add_to_active_list - add spu to active list
* @spu: spu to add to the active list
@@ -437,10 +472,15 @@ int __init spu_sched_init(void)
{
int i;
+ spu_sched_wq = create_singlethread_workqueue("spusched");
+ if (!spu_sched_wq)
+ return 1;
+
spu_prio = kzalloc(sizeof(struct spu_prio_array), GFP_KERNEL);
if (!spu_prio) {
printk(KERN_WARNING "%s: Unable to allocate priority queue.\n",
__FUNCTION__);
+ destroy_workqueue(spu_sched_wq);
return 1;
}
for (i = 0; i < MAX_PRIO; i++) {
@@ -471,4 +511,5 @@ void __exit spu_sched_exit(void)
mutex_unlock(&spu_prio->active_mutex[node]);
}
kfree(spu_prio);
+ destroy_workqueue(spu_sched_wq);
}

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