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authorSuresh Siddha <suresh.b.siddha@intel.com>2008-03-10 15:28:05 -0700
committerIngo Molnar <mingo@elte.hu>2008-04-19 19:19:55 +0200
commitaa283f49276e7d840a40fb01eee6de97eaa7e012 (patch)
treeb17b134b174666e482b1a8ad486436a3d5cdb83e /arch/x86/kernel/i387.c
parent61c4628b538608c1a85211ed8438136adfeb9a95 (diff)
downloadblackbird-op-linux-aa283f49276e7d840a40fb01eee6de97eaa7e012.tar.gz
blackbird-op-linux-aa283f49276e7d840a40fb01eee6de97eaa7e012.zip
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>
Diffstat (limited to 'arch/x86/kernel/i387.c')
-rw-r--r--arch/x86/kernel/i387.c38
1 files changed, 30 insertions, 8 deletions
diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index baf632b221d4..db6839b53195 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -8,7 +8,6 @@
#include <linux/module.h>
#include <linux/regset.h>
#include <linux/sched.h>
-#include <linux/bootmem.h>
#include <asm/sigcontext.h>
#include <asm/processor.h>
@@ -63,7 +62,6 @@ void __init init_thread_xstate(void)
else
xstate_size = sizeof(struct i387_fsave_struct);
#endif
- init_task.thread.xstate = alloc_bootmem(xstate_size);
}
#ifdef CONFIG_X86_64
@@ -93,12 +91,22 @@ void __cpuinit fpu_init(void)
* value at reset if we support XMM instructions and then
* remeber the current task has used the FPU.
*/
-void init_fpu(struct task_struct *tsk)
+int init_fpu(struct task_struct *tsk)
{
if (tsk_used_math(tsk)) {
if (tsk == current)
unlazy_fpu(tsk);
- return;
+ return 0;
+ }
+
+ /*
+ * Memory allocation at the first usage of the FPU and other state.
+ */
+ if (!tsk->thread.xstate) {
+ tsk->thread.xstate = kmem_cache_alloc(task_xstate_cachep,
+ GFP_KERNEL);
+ if (!tsk->thread.xstate)
+ return -ENOMEM;
}
if (cpu_has_fxsr) {
@@ -120,6 +128,7 @@ void init_fpu(struct task_struct *tsk)
* Only the device not available exception or ptrace can call init_fpu.
*/
set_stopped_child_used_math(tsk);
+ return 0;
}
int fpregs_active(struct task_struct *target, const struct user_regset *regset)
@@ -136,10 +145,14 @@ int xfpregs_get(struct task_struct *target, const struct user_regset *regset,
unsigned int pos, unsigned int count,
void *kbuf, void __user *ubuf)
{
+ int ret;
+
if (!cpu_has_fxsr)
return -ENODEV;
- init_fpu(target);
+ ret = init_fpu(target);
+ if (ret)
+ return ret;
return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
&target->thread.xstate->fxsave, 0, -1);
@@ -154,7 +167,10 @@ int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
if (!cpu_has_fxsr)
return -ENODEV;
- init_fpu(target);
+ ret = init_fpu(target);
+ if (ret)
+ return ret;
+
set_stopped_child_used_math(target);
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
@@ -312,11 +328,14 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset,
void *kbuf, void __user *ubuf)
{
struct user_i387_ia32_struct env;
+ int ret;
if (!HAVE_HWFP)
return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);
- init_fpu(target);
+ ret = init_fpu(target);
+ if (ret)
+ return ret;
if (!cpu_has_fxsr) {
return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
@@ -344,7 +363,10 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset,
if (!HAVE_HWFP)
return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf);
- init_fpu(target);
+ ret = init_fpu(target);
+ if (ret)
+ return ret;
+
set_stopped_child_used_math(target);
if (!cpu_has_fxsr) {
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