The patch titled
sLeAZY FPU feature: i386 support
has been added to the -mm tree. Its filename is
sleazy-fpu-feature-i386-support.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: sLeAZY FPU feature: i386 support
From: Chuck Ebbert <76306.1226@xxxxxxxxxxxxxx>
i386 port of the sLeAZY-fpu feature.
Chuck reports that this gives him a +/- 0.4% improvement on his
simple benchmark
Signed-off-by: Chuck Ebbert <76306.1226@xxxxxxxxxxxxxx>
Signed-off-by: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
arch/i386/kernel/process.c | 12 ++++++++++++
arch/i386/kernel/traps.c | 3 ++-
include/asm-i386/i387.h | 5 ++++-
3 files changed, 18 insertions(+), 2 deletions(-)
diff -puN arch/i386/kernel/process.c~sleazy-fpu-feature-i386-support arch/i386/kernel/process.c
--- a/arch/i386/kernel/process.c~sleazy-fpu-feature-i386-support
+++ a/arch/i386/kernel/process.c
@@ -630,6 +630,11 @@ struct task_struct fastcall * __switch_t
__unlazy_fpu(prev_p);
+
+ /* we're going to use this soon, after a few expensive things */
+ if (next_p->fpu_counter > 5)
+ prefetch(&next->i387.fxsave);
+
/*
* Reload esp0.
*/
@@ -688,6 +693,13 @@ struct task_struct fastcall * __switch_t
disable_tsc(prev_p, next_p);
+ /* If the task has used fpu the last 5 timeslices, just do a full
+ * restore of the math state immediately to avoid the trap; the
+ * chances of needing FPU soon are obviously high now
+ */
+ if (next_p->fpu_counter > 5)
+ math_state_restore();
+
return prev_p;
}
diff -puN arch/i386/kernel/traps.c~sleazy-fpu-feature-i386-support arch/i386/kernel/traps.c
--- a/arch/i386/kernel/traps.c~sleazy-fpu-feature-i386-support
+++ a/arch/i386/kernel/traps.c
@@ -1060,7 +1060,7 @@ fastcall unsigned char * fixup_x86_bogus
* Must be called with kernel preemption disabled (in this case,
* local interrupts are disabled at the call-site in entry.S).
*/
-asmlinkage void math_state_restore(struct pt_regs regs)
+asmlinkage void math_state_restore(void)
{
struct thread_info *thread = current_thread_info();
struct task_struct *tsk = thread->task;
@@ -1070,6 +1070,7 @@ asmlinkage void math_state_restore(struc
init_fpu(tsk);
restore_fpu(tsk);
thread->status |= TS_USEDFPU; /* So we fnsave on switch_to() */
+ tsk->fpu_counter++;
}
#ifndef CONFIG_MATH_EMULATION
diff -puN include/asm-i386/i387.h~sleazy-fpu-feature-i386-support include/asm-i386/i387.h
--- a/include/asm-i386/i387.h~sleazy-fpu-feature-i386-support
+++ a/include/asm-i386/i387.h
@@ -76,7 +76,9 @@ static inline void __save_init_fpu( stru
#define __unlazy_fpu( tsk ) do { \
if (task_thread_info(tsk)->status & TS_USEDFPU) \
- save_init_fpu( tsk ); \
+ save_init_fpu( tsk ); \
+ else \
+ tsk->fpu_counter = 0; \
} while (0)
#define __clear_fpu( tsk ) \
@@ -118,6 +120,7 @@ static inline void save_init_fpu( struct
extern unsigned short get_fpu_cwd( struct task_struct *tsk );
extern unsigned short get_fpu_swd( struct task_struct *tsk );
extern unsigned short get_fpu_mxcsr( struct task_struct *tsk );
+extern asmlinkage void math_state_restore(void);
/*
* Signal frame handlers...
_
Patches currently in -mm which might be from 76306.1226@xxxxxxxxxxxxxx are
origin.patch
i386-print-stack-size-in-oops-messages.patch
sleazy-fpu-feature-i386-support.patch
binfmt_elf-fix-checks-for-bad-address.patch
binfmt_elf-fix-checks-for-bad-address-fix.patch
-
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