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[PATCH] i386: add idle notifier

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Add a notifier mechanism to the low level idle loop.  You can register a
callback function which gets invoked on entry and exit from the low level idle
loop.  The low level idle loop is defined as the polling loop, low-power call,
or the mwait instruction.  Interrupts processed by the idle thread are not
considered part of the low level loop.

The notifier can be used to measure precisely how much is spent in useless
execution (or low power mode).  The perfmon subsystem uses it to turn on/off
monitoring.

Signed-off-by: stephane eranian <eranian@hpl.hp.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Andi Kleen <ak@suse.de>
This commit is contained in:
Stephane Eranian
2007-02-13 13:26:22 +01:00
committed by Andi Kleen
parent 86a978837c
commit 2ff2d3d747
7 changed files with 85 additions and 1 deletions
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8
include/asm-i386/processor.h
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@@ -257,6 +257,14 @@ static inline void __mwait(unsigned long eax, unsigned long ecx)
: :"a" (eax), "c" (ecx));
}
static inline void __sti_mwait(unsigned long eax, unsigned long ecx)
{
/* "mwait %eax,%ecx;" */
asm volatile(
"sti; .byte 0x0f,0x01,0xc9;"
: :"a" (eax), "c" (ecx));
}
extern void mwait_idle_with_hints(unsigned long eax, unsigned long ecx);
/* from system description table in BIOS. Mostly for MCA use, but