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x86, fpu: lazy allocation of FPU area - v5

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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>
This commit is contained in:
Suresh Siddha
2008-03-10 15:28:05 -07:00
committed by Ingo Molnar
parent 61c4628b53
commit aa283f4927
8 changed files with 91 additions and 23 deletions
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28
arch/x86/kernel/process.c
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@@ -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));
}