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Commit c375f15a authored by Vineet Gupta's avatar Vineet Gupta Committed by Linus Torvalds
Browse files

x86: move fpu_counter into ARCH specific thread_struct 



Only a couple of arches (sh/x86) use fpu_counter in task_struct so it can
be moved out into ARCH specific thread_struct, reducing the size of
task_struct for other arches.

Compile tested i386_defconfig + gcc 4.7.3

Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
Acked-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Paul Mundt <paul.mundt@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 616c05d1

arch/x86/include/asm/fpu-internal.h

+5 −5
Original line number Diff line number Diff line
@@ -365,7 +365,7 @@ static inline void drop_fpu(struct task_struct *tsk) 
	 * Forget coprocessor state..

	 */

	preempt_disable();

	tsk->fpu_counter = 0;

	tsk->thread.fpu_counter = 0;

	__drop_fpu(tsk);

	clear_used_math();

	preempt_enable();
@@ -424,7 +424,7 @@ 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->fpu_counter > 5);

					     new->thread.fpu_counter > 5);

	if (__thread_has_fpu(old)) {

		if (!__save_init_fpu(old))

			cpu = ~0;
@@ -433,16 +433,16 @@ 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->fpu_counter++;

			new->thread.fpu_counter++;

			__thread_set_has_fpu(new);

			prefetch(new->thread.fpu.state);

		} else if (!use_eager_fpu())

			stts();

	} else {

		old->fpu_counter = 0;

		old->thread.fpu_counter = 0;

		old->thread.fpu.last_cpu = ~0;

		if (fpu.preload) {

			new->fpu_counter++;

			new->thread.fpu_counter++;

			if (!use_eager_fpu() && fpu_lazy_restore(new, cpu))

				fpu.preload = 0;

			else

arch/x86/include/asm/processor.h

+9 −0
Original line number Diff line number Diff line
@@ -488,6 +488,15 @@ 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;

};



/*

arch/x86/kernel/i387.c

+1 −1
Original line number Diff line number Diff line
@@ -100,7 +100,7 @@ void unlazy_fpu(struct task_struct *tsk) 
		__save_init_fpu(tsk);

		__thread_fpu_end(tsk);

	} else

		tsk->fpu_counter = 0;

		tsk->thread.fpu_counter = 0;

	preempt_enable();

}

EXPORT_SYMBOL(unlazy_fpu);

arch/x86/kernel/process_32.c

+2 −2
Original line number Diff line number Diff line
@@ -153,7 +153,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, 
		childregs->orig_ax = -1;

		childregs->cs = __KERNEL_CS | get_kernel_rpl();

		childregs->flags = X86_EFLAGS_IF | X86_EFLAGS_FIXED;

		p->fpu_counter = 0;

		p->thread.fpu_counter = 0;

		p->thread.io_bitmap_ptr = NULL;

		memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));

		return 0;
@@ -166,7 +166,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, 
	p->thread.ip = (unsigned long) ret_from_fork;

	task_user_gs(p) = get_user_gs(current_pt_regs());



	p->fpu_counter = 0;

	p->thread.fpu_counter = 0;

	p->thread.io_bitmap_ptr = NULL;

	tsk = current;

	err = -ENOMEM;

arch/x86/kernel/process_64.c

+1 −1
Original line number Diff line number Diff line
@@ -163,7 +163,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, 
	p->thread.sp = (unsigned long) childregs;

	p->thread.usersp = me->thread.usersp;

	set_tsk_thread_flag(p, TIF_FORK);

	p->fpu_counter = 0;

	p->thread.fpu_counter = 0;

	p->thread.io_bitmap_ptr = NULL;



	savesegment(gs, p->thread.gsindex);