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x86/fpu: Move thread_info::fpu_counter into thread_info::fpu.counter 

This field is kept separate from the main FPU state structure for
no good reason.

Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar 2015-04-22 09:52:56 +02:00
parent 3f6a0bce90
commit c0c2803dee
4 changed files with 16 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
arch/x86/include/asm/fpu-internal.h
View File

@ -384,7 +384,7 @@ static inline void drop_fpu(struct task_struct *tsk)
* Forget coprocessor state..
*/
preempt_disable();
tsk->thread.fpu_counter = 0;
tsk->thread.fpu.counter = 0;
if (__thread_has_fpu(tsk)) {
/* Ignore delayed exceptions from user space */
@ -441,7 +441,7 @@ static inline fpu_switch_t switch_fpu_prepare(struct task_struct *old, struct ta
* or if the past 5 consecutive context-switches used math.
*/
fpu.preload = tsk_used_math(new) &&
(use_eager_fpu() || new->thread.fpu_counter > 5);
(use_eager_fpu() || new->thread.fpu.counter > 5);
if (__thread_has_fpu(old)) {
if (!__save_init_fpu(old))
@ -454,16 +454,16 @@ static inline fpu_switch_t switch_fpu_prepare(struct task_struct *old, struct ta
/* Don't change CR0.TS if we just switch! */
if (fpu.preload) {
new->thread.fpu_counter++;
new->thread.fpu.counter++;
__thread_set_has_fpu(new);
prefetch(new->thread.fpu.state);
} else if (!use_eager_fpu())
stts();
} else {
old->thread.fpu_counter = 0;
old->thread.fpu.counter = 0;
task_disable_lazy_fpu_restore(old);
if (fpu.preload) {
new->thread.fpu_counter++;
new->thread.fpu.counter++;
if (fpu_lazy_restore(new, cpu))
fpu.preload = 0;
else

18
arch/x86/include/asm/processor.h
View File

@ -433,6 +433,15 @@ struct fpu {
unsigned int last_cpu;
unsigned int has_fpu;
union thread_xstate *state;
/*
* This counter contains the number of consecutive context switches
* that the FPU is used. If this is over a threshold, the lazy fpu
* saving becomes unlazy to save the trap. This is an unsigned char
* so that after 256 times the counter wraps and the behavior turns
* lazy again; this to deal with bursty apps that only use FPU for
* a short time
*/
unsigned char counter;
};
#ifdef CONFIG_X86_64
@ -535,15 +544,6 @@ struct thread_struct {
unsigned long iopl;
/* Max allowed port in the bitmap, in bytes: */
unsigned io_bitmap_max;
/*
* fpu_counter contains the number of consecutive context switches
* that the FPU is used. If this is over a threshold, the lazy fpu
* saving becomes unlazy to save the trap. This is an unsigned char
* so that after 256 times the counter wraps and the behavior turns
* lazy again; this to deal with bursty apps that only use FPU for
* a short time
*/
unsigned char fpu_counter;
};
/*

2
arch/x86/kernel/process.c
View File

@ -87,7 +87,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
{
*dst = *src;
dst->thread.fpu_counter = 0;
dst->thread.fpu.counter = 0;
dst->thread.fpu.has_fpu = 0;
dst->thread.fpu.state = NULL;
task_disable_lazy_fpu_restore(dst);

2
arch/x86/kernel/traps.c
View File

@ -863,7 +863,7 @@ void math_state_restore(void)
fpu_reset_state(tsk);
force_sig_info(SIGSEGV, SEND_SIG_PRIV, tsk);
} else {
tsk->thread.fpu_counter++;
tsk->thread.fpu.counter++;
}
kernel_fpu_enable();
}