On Tue, Sep 17, 2013 at 11:47:17AM +0530, Vineet Gupta wrote:
> 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 sh defconfig + sh4-linux-gcc (4.6.3)
>
> Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
> Cc: Paul Mundt <lethal@xxxxxxxxxxxx>
> Cc: Michel Lespinasse <walken@xxxxxxxxxx>
> Cc: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Jesper Nilsson <jesper.nilsson@xxxxxxxx>
> Cc: Chris Metcalf <cmetcalf@xxxxxxxxxx>
> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: linux-arch@xxxxxxxxxxxxxxx
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: linux-sh@xxxxxxxxxxxxxxx
Your mailer didn't actually pick up any of those and I'm sure Paul Mundt
would love to see patches to his arch land in his Inbox.. Added him to
CC.
> ---
> arch/sh/include/asm/fpu.h | 2 +-
> arch/sh/include/asm/processor_32.h | 10 ++++++++++
> arch/sh/include/asm/processor_64.h | 10 ++++++++++
> arch/sh/kernel/cpu/fpu.c | 2 +-
> arch/sh/kernel/process_32.c | 6 +++---
> 5 files changed, 25 insertions(+), 5 deletions(-)
>
> diff --git a/arch/sh/include/asm/fpu.h b/arch/sh/include/asm/fpu.h
> index 06c4281..09fc2bc 100644
> --- a/arch/sh/include/asm/fpu.h
> +++ b/arch/sh/include/asm/fpu.h
> @@ -46,7 +46,7 @@ static inline void __unlazy_fpu(struct task_struct *tsk, struct pt_regs *regs)
> save_fpu(tsk);
> release_fpu(regs);
> } else
> - tsk->fpu_counter = 0;
> + tsk->thread.fpu_counter = 0;
> }
>
> static inline void unlazy_fpu(struct task_struct *tsk, struct pt_regs *regs)
> diff --git a/arch/sh/include/asm/processor_32.h b/arch/sh/include/asm/processor_32.h
> index e699a12..18e0377 100644
> --- a/arch/sh/include/asm/processor_32.h
> +++ b/arch/sh/include/asm/processor_32.h
> @@ -111,6 +111,16 @@ struct thread_struct {
>
> /* Extended processor state */
> union thread_xstate *xstate;
> +
> + /*
> + * 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;
> };
>
> #define INIT_THREAD { \
> diff --git a/arch/sh/include/asm/processor_64.h b/arch/sh/include/asm/processor_64.h
> index 1cc7d31..eedd4f6 100644
> --- a/arch/sh/include/asm/processor_64.h
> +++ b/arch/sh/include/asm/processor_64.h
> @@ -126,6 +126,16 @@ struct thread_struct {
>
> /* floating point info */
> union thread_xstate *xstate;
> +
> + /*
> + * 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;
> };
>
> #define INIT_MMAP \
> diff --git a/arch/sh/kernel/cpu/fpu.c b/arch/sh/kernel/cpu/fpu.c
> index f8f7af5..4e33224 100644
> --- a/arch/sh/kernel/cpu/fpu.c
> +++ b/arch/sh/kernel/cpu/fpu.c
> @@ -44,7 +44,7 @@ void __fpu_state_restore(void)
> restore_fpu(tsk);
>
> task_thread_info(tsk)->status |= TS_USEDFPU;
> - tsk->fpu_counter++;
> + tsk->thread.fpu_counter++;
> }
>
> void fpu_state_restore(struct pt_regs *regs)
> diff --git a/arch/sh/kernel/process_32.c b/arch/sh/kernel/process_32.c
> index ebd3933..2885fc9 100644
> --- a/arch/sh/kernel/process_32.c
> +++ b/arch/sh/kernel/process_32.c
> @@ -156,7 +156,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
> #endif
> ti->addr_limit = KERNEL_DS;
> ti->status &= ~TS_USEDFPU;
> - p->fpu_counter = 0;
> + p->thread.fpu_counter = 0;
> return 0;
> }
> *childregs = *current_pt_regs();
> @@ -189,7 +189,7 @@ __switch_to(struct task_struct *prev, struct task_struct *next)
> unlazy_fpu(prev, task_pt_regs(prev));
>
> /* we're going to use this soon, after a few expensive things */
> - if (next->fpu_counter > 5)
> + if (next->thread.fpu_counter > 5)
> prefetch(next_t->xstate);
>
> #ifdef CONFIG_MMU
> @@ -207,7 +207,7 @@ __switch_to(struct task_struct *prev, struct task_struct *next)
> * restore of the math state immediately to avoid the trap; the
> * chances of needing FPU soon are obviously high now
> */
> - if (next->fpu_counter > 5)
> + if (next->thread.fpu_counter > 5)
> __fpu_state_restore();
>
> return prev;
> --
> 1.8.1.2
>
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