How do wake timers work?
Windows most commonly places a computer in S3 (standby/save-to-RAM) mode, where power is cut from the CPU but not to RAM.
If power is cut to the CPU, then how are wake timers triggered? Which component knows when to automatically wake the computer up?
If it is in the BIOS, how does Windows inform the BIOS of the next wakeup time?
sleep wake-up
asked Aug 2 '15 at 19:20
oldmud0oldmud0
3,09131536
add a comment |
Windows most commonly places a computer in S3 (standby/save-to-RAM) mode, where power is cut from the CPU but not to RAM.
If power is cut to the CPU, then how are wake timers triggered? Which component knows when to automatically wake the computer up?
If it is in the BIOS, how does Windows inform the BIOS of the next wakeup time?
sleep wake-up
asked Aug 2 '15 at 19:20
oldmud0oldmud0
3,09131536
add a comment |
Windows most commonly places a computer in S3 (standby/save-to-RAM) mode, where power is cut from the CPU but not to RAM.
If power is cut to the CPU, then how are wake timers triggered? Which component knows when to automatically wake the computer up?
If it is in the BIOS, how does Windows inform the BIOS of the next wakeup time?
sleep wake-up
asked Aug 2 '15 at 19:20
oldmud0oldmud0
3,09131536
Windows most commonly places a computer in S3 (standby/save-to-RAM) mode, where power is cut from the CPU but not to RAM.
If power is cut to the CPU, then how are wake timers triggered? Which component knows when to automatically wake the computer up?
If it is in the BIOS, how does Windows inform the BIOS of the next wakeup time?
sleep wake-up
sleep wake-up
asked Aug 2 '15 at 19:20
oldmud0oldmud0
3,09131536
asked Aug 2 '15 at 19:20
oldmud0oldmud0
3,09131536
asked Aug 2 '15 at 19:20
oldmud0oldmud0
3,09131536
asked Aug 2 '15 at 19:20
oldmud0oldmud0
3,09131536
asked Aug 2 '15 at 19:20
oldmud0oldmud0
3,09131536
3,09131536
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
This is done via the "alarm" registers in the RTC (real-time clock). On the original PC-AT, this chip was a Motorola MC146818.
Before going to sleep (ACPI S3), the kernel will program the next-scheduled wake-up time into the "alarm" registers on the RTC, which is always powered-on. When this wake-up time arrives, the RTC will trigger the chipset to power-on the system, and resume from S3. (Note that in most modern systems, the RTC is actually part of the southbridge itself, so the power-on signalling happens internally).
After the system resumes from sleep, the kernel will evaluate its list of pending wake events, dispatching the ones that have arrived.
This paper from Intel describes the interface (for x86 systems):
Accessing the Real Time Clock Registers and the NMI Enable Bit
The programming of these registers is done in the Linux kernel in cmos_set_alarm.
answered Aug 2 '15 at 19:32
Jonathon ReinhartJonathon Reinhart
1,85262549
add a comment |
A wake timer is a timed event that wakes the PC from sleep and hibernate states at a specific time. For example, a task in Task Scheduler set with the "Wake the computer to run this task" check box checked.
Important wake timers are a new class of wake timer in Windows 10 that includes things like reboots after a Windows update that requires one. They supersede all other settings.
This tutorial will show you how to enable or disable to allow wake timers to wake the computer in Windows 10.
To Enable or Disable Allow Wake Timers in Power Options
Open the advanced power settings of a power plan you want to enable or disable wake timers for.
Expand open Sleep and Allow wake timers. Select Enable, Disable (default on battery), or Important Wake Timers Only (default plugged in) for what you want, and click/tap on OK.
answered Jan 19 at 8:58
Bryan GreeneBryan Greene
1
You have defined “wake timer” and given some information on how they are used. But you have not answered the question: how do they work?
– Scott
Jan 19 at 9:35
add a comment |
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2 Answers
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active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
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active
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votes
This is done via the "alarm" registers in the RTC (real-time clock). On the original PC-AT, this chip was a Motorola MC146818.
Before going to sleep (ACPI S3), the kernel will program the next-scheduled wake-up time into the "alarm" registers on the RTC, which is always powered-on. When this wake-up time arrives, the RTC will trigger the chipset to power-on the system, and resume from S3. (Note that in most modern systems, the RTC is actually part of the southbridge itself, so the power-on signalling happens internally).
After the system resumes from sleep, the kernel will evaluate its list of pending wake events, dispatching the ones that have arrived.
This paper from Intel describes the interface (for x86 systems):
Accessing the Real Time Clock Registers and the NMI Enable Bit
The programming of these registers is done in the Linux kernel in cmos_set_alarm.
answered Aug 2 '15 at 19:32
Jonathon ReinhartJonathon Reinhart
1,85262549
add a comment |
This is done via the "alarm" registers in the RTC (real-time clock). On the original PC-AT, this chip was a Motorola MC146818.
Before going to sleep (ACPI S3), the kernel will program the next-scheduled wake-up time into the "alarm" registers on the RTC, which is always powered-on. When this wake-up time arrives, the RTC will trigger the chipset to power-on the system, and resume from S3. (Note that in most modern systems, the RTC is actually part of the southbridge itself, so the power-on signalling happens internally).
After the system resumes from sleep, the kernel will evaluate its list of pending wake events, dispatching the ones that have arrived.
This paper from Intel describes the interface (for x86 systems):
Accessing the Real Time Clock Registers and the NMI Enable Bit
The programming of these registers is done in the Linux kernel in cmos_set_alarm.
answered Aug 2 '15 at 19:32
Jonathon ReinhartJonathon Reinhart
1,85262549
add a comment |
This is done via the "alarm" registers in the RTC (real-time clock). On the original PC-AT, this chip was a Motorola MC146818.
Before going to sleep (ACPI S3), the kernel will program the next-scheduled wake-up time into the "alarm" registers on the RTC, which is always powered-on. When this wake-up time arrives, the RTC will trigger the chipset to power-on the system, and resume from S3. (Note that in most modern systems, the RTC is actually part of the southbridge itself, so the power-on signalling happens internally).
After the system resumes from sleep, the kernel will evaluate its list of pending wake events, dispatching the ones that have arrived.
This paper from Intel describes the interface (for x86 systems):
Accessing the Real Time Clock Registers and the NMI Enable Bit
The programming of these registers is done in the Linux kernel in cmos_set_alarm.
answered Aug 2 '15 at 19:32
Jonathon ReinhartJonathon Reinhart
1,85262549
This is done via the "alarm" registers in the RTC (real-time clock). On the original PC-AT, this chip was a Motorola MC146818.
Before going to sleep (ACPI S3), the kernel will program the next-scheduled wake-up time into the "alarm" registers on the RTC, which is always powered-on. When this wake-up time arrives, the RTC will trigger the chipset to power-on the system, and resume from S3. (Note that in most modern systems, the RTC is actually part of the southbridge itself, so the power-on signalling happens internally).
After the system resumes from sleep, the kernel will evaluate its list of pending wake events, dispatching the ones that have arrived.
This paper from Intel describes the interface (for x86 systems):
Accessing the Real Time Clock Registers and the NMI Enable Bit
The programming of these registers is done in the Linux kernel in cmos_set_alarm.
answered Aug 2 '15 at 19:32
Jonathon ReinhartJonathon Reinhart
1,85262549
edited Jan 19 at 5:19
answered Aug 2 '15 at 19:32
Jonathon ReinhartJonathon Reinhart
1,85262549
answered Aug 2 '15 at 19:32
Jonathon ReinhartJonathon Reinhart
1,85262549
answered Aug 2 '15 at 19:32
Jonathon ReinhartJonathon Reinhart
1,85262549
1,85262549
add a comment |
add a comment |
A wake timer is a timed event that wakes the PC from sleep and hibernate states at a specific time. For example, a task in Task Scheduler set with the "Wake the computer to run this task" check box checked.
Important wake timers are a new class of wake timer in Windows 10 that includes things like reboots after a Windows update that requires one. They supersede all other settings.
This tutorial will show you how to enable or disable to allow wake timers to wake the computer in Windows 10.
To Enable or Disable Allow Wake Timers in Power Options
Open the advanced power settings of a power plan you want to enable or disable wake timers for.
Expand open Sleep and Allow wake timers. Select Enable, Disable (default on battery), or Important Wake Timers Only (default plugged in) for what you want, and click/tap on OK.
answered Jan 19 at 8:58
Bryan GreeneBryan Greene
1
You have defined “wake timer” and given some information on how they are used. But you have not answered the question: how do they work?
– Scott
Jan 19 at 9:35
add a comment |
A wake timer is a timed event that wakes the PC from sleep and hibernate states at a specific time. For example, a task in Task Scheduler set with the "Wake the computer to run this task" check box checked.
Important wake timers are a new class of wake timer in Windows 10 that includes things like reboots after a Windows update that requires one. They supersede all other settings.
This tutorial will show you how to enable or disable to allow wake timers to wake the computer in Windows 10.
To Enable or Disable Allow Wake Timers in Power Options
Open the advanced power settings of a power plan you want to enable or disable wake timers for.
Expand open Sleep and Allow wake timers. Select Enable, Disable (default on battery), or Important Wake Timers Only (default plugged in) for what you want, and click/tap on OK.
answered Jan 19 at 8:58
Bryan GreeneBryan Greene
1
You have defined “wake timer” and given some information on how they are used. But you have not answered the question: how do they work?
– Scott
Jan 19 at 9:35
add a comment |
A wake timer is a timed event that wakes the PC from sleep and hibernate states at a specific time. For example, a task in Task Scheduler set with the "Wake the computer to run this task" check box checked.
Important wake timers are a new class of wake timer in Windows 10 that includes things like reboots after a Windows update that requires one. They supersede all other settings.
This tutorial will show you how to enable or disable to allow wake timers to wake the computer in Windows 10.
To Enable or Disable Allow Wake Timers in Power Options
Open the advanced power settings of a power plan you want to enable or disable wake timers for.
Expand open Sleep and Allow wake timers. Select Enable, Disable (default on battery), or Important Wake Timers Only (default plugged in) for what you want, and click/tap on OK.
answered Jan 19 at 8:58
Bryan GreeneBryan Greene
1
A wake timer is a timed event that wakes the PC from sleep and hibernate states at a specific time. For example, a task in Task Scheduler set with the "Wake the computer to run this task" check box checked.
Important wake timers are a new class of wake timer in Windows 10 that includes things like reboots after a Windows update that requires one. They supersede all other settings.
This tutorial will show you how to enable or disable to allow wake timers to wake the computer in Windows 10.
To Enable or Disable Allow Wake Timers in Power Options
Open the advanced power settings of a power plan you want to enable or disable wake timers for.
Expand open Sleep and Allow wake timers. Select Enable, Disable (default on battery), or Important Wake Timers Only (default plugged in) for what you want, and click/tap on OK.
answered Jan 19 at 8:58
Bryan GreeneBryan Greene
1
answered Jan 19 at 8:58
Bryan GreeneBryan Greene
1
answered Jan 19 at 8:58
Bryan GreeneBryan Greene
1
answered Jan 19 at 8:58
Bryan GreeneBryan Greene
1
1
You have defined “wake timer” and given some information on how they are used. But you have not answered the question: how do they work?
– Scott
Jan 19 at 9:35
add a comment |
You have defined “wake timer” and given some information on how they are used. But you have not answered the question: how do they work?
– Scott
Jan 19 at 9:35
You have defined “wake timer” and given some information on how they are used. But you have not answered the question: how do they work?
– Scott
Jan 19 at 9:35
You have defined “wake timer” and given some information on how they are used. But you have not answered the question: how do they work?
– Scott
Jan 19 at 9:35
add a comment |
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