On 13-09-17 02:17 AM, Vineet Gupta wrote:
> Only a couple of arches (sh/x86) use fpu_counter in task_struct so it
Wouldn't it make sense to also have the arch/sh changes here in
this same commit then, rather than breaking their build?
Paul.
--
> 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: Vineet Gupta <vgupta@xxxxxxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
> Cc: x86@xxxxxxxxxx
> Cc: Suresh Siddha <suresh.b.siddha@xxxxxxxxx>
> Cc: Borislav Petkov <bp@xxxxxxx>
> Cc: Vincent Palatin <vpalatin@xxxxxxxxxxxx>
> Cc: Len Brown <len.brown@xxxxxxxxx>
> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> Cc: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
> Cc: Pekka Riikonen <priikone@xxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Dave Jones <davej@xxxxxxxxxx>
> Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
> Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> ---
> arch/x86/include/asm/fpu-internal.h | 10 +++++-----
> arch/x86/include/asm/processor.h | 9 +++++++++
> arch/x86/kernel/i387.c | 2 +-
> arch/x86/kernel/process_32.c | 4 ++--
> arch/x86/kernel/process_64.c | 2 +-
> arch/x86/kernel/traps.c | 2 +-
> 6 files changed, 19 insertions(+), 10 deletions(-)
>
> diff --git a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h
> index 4d0bda7..c49a613 100644
> --- a/arch/x86/include/asm/fpu-internal.h
> +++ b/arch/x86/include/asm/fpu-internal.h
> @@ -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
> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> index 987c75e..7b034a4 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -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;
> };
>
> /*
> diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
> index 5d576ab..e8368c6 100644
> --- a/arch/x86/kernel/i387.c
> +++ b/arch/x86/kernel/i387.c
> @@ -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);
> diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
> index 884f98f..6af43b0 100644
> --- a/arch/x86/kernel/process_32.c
> +++ b/arch/x86/kernel/process_32.c
> @@ -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;
> diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
> index bb1dc51..bbab295 100644
> --- a/arch/x86/kernel/process_64.c
> +++ b/arch/x86/kernel/process_64.c
> @@ -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);
> diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
> index 8c8093b..64b980f 100644
> --- a/arch/x86/kernel/traps.c
> +++ b/arch/x86/kernel/traps.c
> @@ -653,7 +653,7 @@ void math_state_restore(void)
> return;
> }
>
> - tsk->fpu_counter++;
> + tsk->thread.fpu_counter++;
> }
> EXPORT_SYMBOL_GPL(math_state_restore);
>
>
--
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