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Date: Wed, 9 Oct 2013 11:09:29 +0530
From: Vineet Gupta <Vineet.Gupta1@...opsys.com>
To: Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Paul Mundt <paul.mundt@...il.com>
CC: <linux-arch@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
Vineet Gupta <Vineet.Gupta1@...opsys.com>,
Vineet Gupta <Vineet.Gupta1@...opsys.com>, <x86@...nel.org>
Subject: [PATCH v2 2/3] x86: Move fpu_counter into ARCH specific thread_struct
From: Vineet Gupta <Vineet.Gupta1@...opsys.com>
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: Vineet Gupta <vgupta@...opsys.com>
Acked-by: Ingo Molnar <mingo@...nel.org>
Cc: x86@...nel.org
---
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 4d0bda7b11e3..c49a613c6452 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 987c75ecc334..7b034a4057f9 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 5d576ab34403..e8368c6dd2a2 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 884f98f69354..6af43b03c8ef 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 bb1dc51bab05..bbab295ca558 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 8c8093b146ca..64b980f16660 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);
--
1.8.1.2
--
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