x86, fpu: lazy allocation of FPU area - v5
Only allocate the FPU area when the application actually uses FPU, i.e., in the
first lazy FPU trap. This could save memory for non-fpu using apps.
for example: on my system after boot, there are around 300 processes, with
only 17 using FPU.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index ead24ef..0e613e7 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -5,24 +5,34 @@
#include <linux/slab.h>
#include <linux/sched.h>
-static struct kmem_cache *task_xstate_cachep;
+struct kmem_cache *task_xstate_cachep;
int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
{
*dst = *src;
- dst->thread.xstate = kmem_cache_alloc(task_xstate_cachep, GFP_KERNEL);
- if (!dst->thread.xstate)
- return -ENOMEM;
- WARN_ON((unsigned long)dst->thread.xstate & 15);
- memcpy(dst->thread.xstate, src->thread.xstate, xstate_size);
+ if (src->thread.xstate) {
+ dst->thread.xstate = kmem_cache_alloc(task_xstate_cachep,
+ GFP_KERNEL);
+ if (!dst->thread.xstate)
+ return -ENOMEM;
+ WARN_ON((unsigned long)dst->thread.xstate & 15);
+ memcpy(dst->thread.xstate, src->thread.xstate, xstate_size);
+ }
return 0;
}
+void free_thread_xstate(struct task_struct *tsk)
+{
+ if (tsk->thread.xstate) {
+ kmem_cache_free(task_xstate_cachep, tsk->thread.xstate);
+ tsk->thread.xstate = NULL;
+ }
+}
+
+
void free_thread_info(struct thread_info *ti)
{
- kmem_cache_free(task_xstate_cachep, ti->task->thread.xstate);
- ti->task->thread.xstate = NULL;
-
+ free_thread_xstate(ti->task);
free_pages((unsigned long)(ti), get_order(THREAD_SIZE));
}