This patch makes restore_fpu() an inline. When L1/L2 cache are saturated
it makes a measurable difference.
Results from profiling Volanomark follow. Sample rate was 2000 samples/sec
(HZ = 250, profile multiplier = 8) on a dual-processor Pentium II Xeon.
Before:
10680 restore_fpu 333.7500
8351 device_not_available 203.6829
3823 math_state_restore 59.7344
-----
22854
After:
12534 math_state_restore 130.5625
8354 device_not_available 203.7561
-----
20888
Patch is "obviously correct" and cuts 9% of the overhead. Please apply.
Next step should be to physically place math_state_restore() after
device_not_available(). Would such a patch be accepted? (Yes it
would be ugly and require linker script changes.)
Signed-off-by: Chuck Ebbert <[EMAIL PROTECTED]>
Index: 2.6.13-rc3a/arch/i386/kernel/i387.c
===================================================================
--- 2.6.13-rc3a.orig/arch/i386/kernel/i387.c
+++ 2.6.13-rc3a/arch/i386/kernel/i387.c
@@ -82,17 +82,6 @@
}
EXPORT_SYMBOL_GPL(kernel_fpu_begin);
-void restore_fpu( struct task_struct *tsk )
-{
- if ( cpu_has_fxsr ) {
- asm volatile( "fxrstor %0"
- : : "m" (tsk->thread.i387.fxsave) );
- } else {
- asm volatile( "frstor %0"
- : : "m" (tsk->thread.i387.fsave) );
- }
-}
-
/*
* FPU tag word conversions.
*/
Index: 2.6.13-rc3a/include/asm-i386/i387.h
===================================================================
--- 2.6.13-rc3a.orig/include/asm-i386/i387.h
+++ 2.6.13-rc3a/include/asm-i386/i387.h
@@ -22,11 +22,20 @@
/*
* FPU lazy state save handling...
*/
-extern void restore_fpu( struct task_struct *tsk );
-
extern void kernel_fpu_begin(void);
#define kernel_fpu_end() do { stts(); preempt_enable(); } while(0)
+static inline void restore_fpu( struct task_struct *tsk )
+{
+ if ( cpu_has_fxsr ) {
+ asm volatile( "fxrstor %0"
+ : : "m" (tsk->thread.i387.fxsave) );
+ } else {
+ asm volatile( "frstor %0"
+ : : "m" (tsk->thread.i387.fsave) );
+ }
+}
+
/*
* These must be called with preempt disabled
*/
__
Chuck
-
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