diff options
| author |   Suresh Siddha <suresh.b.siddha@intel.com> | 2008-03-10 15:28:05 -0700 |
|---|---|---|
| committer |   Ingo Molnar <mingo@elte.hu> | 2008-04-19 19:19:55 +0200 |
| commit | aa283f49276e7d840a40fb01eee6de97eaa7e012 (patch) | |
| tree | b17b134b174666e482b1a8ad486436a3d5cdb83e /arch/x86/kernel/i387.c | |
| parent | x86, fpu: split FPU state from task struct - v5 (diff) | |
| download | linux-dev-aa283f49276e7d840a40fb01eee6de97eaa7e012.tar.xz linux-dev-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.c | 38 |
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) { |