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author | Peter Zijlstra <peterz@infradead.org> | 2013-12-12 15:08:36 +0100 |
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committer | H. Peter Anvin <hpa@linux.intel.com> | 2013-12-19 11:54:44 -0800 |
commit | 16824255394f55adf31b9a96a9965d8c15bdac4c (patch) | |
tree | b28f4a2d59db25700c8b4eafb2e3cfc188c121bc /arch/x86/include/asm/mwait.h | |
parent | 40e2d7f9b5dae048789c64672bf3027fbb663ffa (diff) | |
download | linux-stable-16824255394f55adf31b9a96a9965d8c15bdac4c.tar.gz linux-stable-16824255394f55adf31b9a96a9965d8c15bdac4c.tar.bz2 linux-stable-16824255394f55adf31b9a96a9965d8c15bdac4c.zip |
x86, acpi, idle: Restructure the mwait idle routines
People seem to delight in writing wrong and broken mwait idle routines;
collapse the lot.
This leaves mwait_play_dead() the sole remaining user of __mwait() and
new __mwait() users are probably doing it wrong.
Also remove __sti_mwait() as its unused.
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Jacob Jun Pan <jacob.jun.pan@linux.intel.com>
Cc: Mike Galbraith <bitbucket@online.de>
Cc: Len Brown <lenb@kernel.org>
Cc: Rui Zhang <rui.zhang@intel.com>
Acked-by: Rafael Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20131212141654.616820819@infradead.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/include/asm/mwait.h')
-rw-r--r-- | arch/x86/include/asm/mwait.h | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/arch/x86/include/asm/mwait.h b/arch/x86/include/asm/mwait.h index 2f366d0ac6b4..361b02ef128c 100644 --- a/arch/x86/include/asm/mwait.h +++ b/arch/x86/include/asm/mwait.h @@ -1,6 +1,8 @@ #ifndef _ASM_X86_MWAIT_H #define _ASM_X86_MWAIT_H +#include <linux/sched.h> + #define MWAIT_SUBSTATE_MASK 0xf #define MWAIT_CSTATE_MASK 0xf #define MWAIT_SUBSTATE_SIZE 4 @@ -13,4 +15,42 @@ #define MWAIT_ECX_INTERRUPT_BREAK 0x1 +static inline void __monitor(const void *eax, unsigned long ecx, + unsigned long edx) +{ + /* "monitor %eax, %ecx, %edx;" */ + asm volatile(".byte 0x0f, 0x01, 0xc8;" + :: "a" (eax), "c" (ecx), "d"(edx)); +} + +static inline void __mwait(unsigned long eax, unsigned long ecx) +{ + /* "mwait %eax, %ecx;" */ + asm volatile(".byte 0x0f, 0x01, 0xc9;" + :: "a" (eax), "c" (ecx)); +} + +/* + * This uses new MONITOR/MWAIT instructions on P4 processors with PNI, + * which can obviate IPI to trigger checking of need_resched. + * We execute MONITOR against need_resched and enter optimized wait state + * through MWAIT. Whenever someone changes need_resched, we would be woken + * up from MWAIT (without an IPI). + * + * New with Core Duo processors, MWAIT can take some hints based on CPU + * capability. + */ +static inline void mwait_idle_with_hints(unsigned long eax, unsigned long ecx) +{ + if (!current_set_polling_and_test()) { + if (this_cpu_has(X86_FEATURE_CLFLUSH_MONITOR)) + clflush((void *)¤t_thread_info()->flags); + + __monitor((void *)¤t_thread_info()->flags, 0, 0); + if (!need_resched()) + __mwait(eax, ecx); + } + __current_clr_polling(); +} + #endif /* _ASM_X86_MWAIT_H */ |