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| author | Kyung Min Park <kyung.min.park@intel.com> | 2020-04-24 12:37:56 -0700 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2020-05-07 16:06:20 +0200 |
| commit | cec5f268cd02d25d2d74807843d8ae0292fe0fb7 (patch) | |
| tree | 917947f6e242b5f1c21e136cf3916dd09c3473ce /arch/x86/kernel/time.c | |
| parent | 46f90c7aad62be1af76588108c730d826308a801 (diff) | |
| download | linux-cec5f268cd02d25d2d74807843d8ae0292fe0fb7.tar.gz linux-cec5f268cd02d25d2d74807843d8ae0292fe0fb7.tar.bz2 linux-cec5f268cd02d25d2d74807843d8ae0292fe0fb7.zip | |
x86/delay: Introduce TPAUSE delay
TPAUSE instructs the processor to enter an implementation-dependent
optimized state. The instruction execution wakes up when the time-stamp
counter reaches or exceeds the implicit EDX:EAX 64-bit input value.
The instruction execution also wakes up due to the expiration of
the operating system time-limit or by an external interrupt
or exceptions such as a debug exception or a machine check exception.
TPAUSE offers a choice of two lower power states:
1. Light-weight power/performance optimized state C0.1
2. Improved power/performance optimized state C0.2
This way, it can save power with low wake-up latency in comparison to
spinloop based delay. The selection between the two is governed by the
input register.
TPAUSE is available on processors with X86_FEATURE_WAITPKG.
Co-developed-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Kyung Min Park <kyung.min.park@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/1587757076-30337-4-git-send-email-kyung.min.park@intel.com
Diffstat (limited to 'arch/x86/kernel/time.c')
| -rw-r--r-- | arch/x86/kernel/time.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/kernel/time.c b/arch/x86/kernel/time.c index 106e7f87f534..371a6b348e44 100644 --- a/arch/x86/kernel/time.c +++ b/arch/x86/kernel/time.c @@ -103,6 +103,9 @@ static __init void x86_late_time_init(void) */ x86_init.irqs.intr_mode_init(); tsc_init(); + + if (static_cpu_has(X86_FEATURE_WAITPKG)) + use_tpause_delay(); } /* |