What is the difference between sleep and hibernation in a laptop?

In the beginning of the notebook we can see that in addition to shutdown, restart, logoff there are two, sleep mode and sleep mode, the two modes of what the difference, how to use, the following edit the relevant information to share with you.

Sleep is an energy-saving state that allows your computer to quickly restore full power (usually within a few seconds) when you want to start working again. Getting your computer to sleep is like pausing a DVD player: the computer stops working immediately and is ready to continue working.

Hibernation is a power-saving state that is designed primarily for portable computers. Sleep typically saves work and settings in memory and consumes a small amount of power, while hibernation saves open documents and programs to your hard disk, and then shuts down your computer. In all energy-saving states used by Windows, hibernation uses the least amount of electricity. For laptops, you should use Hibernate mode if you know that you will not use it for a long time, and you cannot charge the battery during that time.

"Mixed Sleep" is primarily designed for desktop computers. Mixed sleep is a combination of sleep and hibernation-it saves all open documents and programs to memory and hard drives, and then lets the computer enter a low-power state so that you can quickly resume work. This way, if a power failure occurs, Windows can recover your work from the hard drive. If you turn on a mixed sleep, the computer goes to sleep, and it automatically goes into a mixed sleep state. On a desktop computer, mixed sleep is usually turned on by default.

1.1 Desktop normal sleep (mixed sleep shutdown), this and XP under the standby is a means, except memory all devices are power off, memory only on DC power (no clock input, this is very important), wake up to restore the power of other devices, and return to working status.

1.2 Desktop hibernation, XP also has this function, the memory of all the data stored in a continuous space on the hard disk, and cut off all power. When recovering, restores the memory data that is temporarily stored in the hard disk to memory and returns to working state.

1.2.1 In the power Plan, the time to go to sleep and into hibernation have a separate set, of course, according to the normal logic of the former is less than the latter. So when you go to sleep has not awakened, until the dormant timer point, the system will automatically save the memory data to the hard disk, disconnect all equipment power, into hibernation.

1.2.2 Mixed sleep, when mixed sleep is open. At the beginning of sleep, the memory data is stored in the hard drive, and the memory is still on the power, into the normal sleep state. In the event of an accidental power outage, the next time you start to restore the data from the hard disk to memory, that is, the principle of hibernation. Of course, if the sleep timer triggers, it automatically goes into hibernation, so there's no need to dump the data because it was already done before. So mixed sleep = sleep + hibernation, which prevents sudden power outages from causing data loss.

1.3 Notebook sleep and Hibernate, the notebook's operating mechanism and desktop are different. In a battery-powered sleep state, if the battery is about to run out, the system will automatically save the memory data into the hard disk and power off, into hibernation. As a result, there are two types of events that can trigger a notebook to sleep into hibernation: the time to hibernate in the power Plan, or the battery is about to run out when the battery is powered.

1.3.1 When the notebook is connected to the AC power, go to sleep, and then disconnect the AC power. When sleep is turned into hibernation, it is still determined by the scheduled time of the "Connect to AC power" in the power Plan. That is, the sleep timer is set when you go to sleep, and you won't be able to set the timer as a "battery powered" plan because you later unplug the AC power.

1.3.2 about a notebook of mixed sleep, you may notice. The machine installed the system, the default is mixed sleep open, in order to prevent the sudden power loss after sleep. And the notebook because of battery power, there is no sudden power failure. Even if the battery is slowly running out, it can be a harbinger of a system that transfers data to the hard disk when the battery is about to run out of hibernation.

　　2. On the question of time

This should be the focus of the debate and the point I want to highlight. There is no doubt that according to the time, sleep is the fastest, followed by hibernation, the slowest is shutdown and boot cold start. Most people who are opposed by the time reason are basically saying, "I am very quick to start the cold, you start slowly because you do not know optimization." I am here to clarify a concept:

2.1 Working status, this concept is very important, that is, you can immediately start working in the system State. I think for many people, some programs must be running, such as QQ, MSN, Mail and other communication software, such as some Office documents (Word, Excel, PPT), such as listening to music software, such as a variety of professional software, such as open a few folders (Resource manager). I just for example, everyone will have their own work status, their work (here is a broad meaning, including entertainment games) state will have a group of open software, system settings. Therefore, to determine whether a program is fast, depends on the time it enters the working state, rather than the pure start time.

2.2 Startup status and working status, some people just forget one side of the ledger, but ignore the other side. Cold start is slow, because loading a large number of DLLs, loading a large number of self starter programs. Ways to reduce startup add-ons to optimize startup speed It's all over the web, but have you ever thought of a problem where the wool was on the sheep. The result is that the more you speed up the startup by reducing the startup items, the farther off the startup and working states are, and it takes a long time to get to work from the startup state. For example, you delete the QQ from the startup items, assuming you have to open a computer QQ, do you manually open QQ do not spend time? Or do you think you have to manually click on it faster than it starts?

2.3 The time advantage of sleep awakening, with a simple example can be explained. Imagine you are writing an article, opened 2 Word documents and a PPT, opened 3-5 Web pages to find information, while opening QQ, MSN, Mail for communication, as well as music software, also opened a number of folders, there may be some professional software such as Visual Studio. Now you're going to bed, get up and write tomorrow. Those who said they optimized the boot, test the machine shut down, and then cold start, into the system after all of these software to open into working state, to see how much time. Even if you start to optimize the better, configure again NB, I do not believe that you can enter the working state in 2 minutes, at least my computer needs 5 minutes. But waking from sleep, getting into work for as long as 10 seconds, this estimate is also conservative, including entering the user password and may need to reconnect ADSL time, 10 seconds is enough. You can start working in 10 seconds!

2.3.1 In fact, the above example is of universal significance, this is a habit of change. People used to save all the documents before shutting down the computer, end all programs, and then leave. And in the sleep mechanism, advocating everyone in any want to leave when the right to press the sleep key, in the recovery can immediately return to the original state. The opening and closing time are omitted, which is the essence of sleep. The example also contains other factors, for example, the time it takes to reopen those pages after a cold start, or even to find those pages (the quickest way to look through the history or the favorites in advance), and wake up to read the open pages directly. Again, if you want to sleep, or dormitory to power off, you play the game has not hit the save inventory how to do? Are you willing to turn off the computer? Hibernation can be a perfect solution to this problem. The essence of the introduction of sleep and dormancy is to keep your work in an instant, so that you can return to work immediately, not only to save time, but also to save people's operations. If it's just a way of starting out, that's a big misunderstanding.

2.4 Hibernate and cold start, the same is from the hard disk load, hibernate recovery speed is still faster than cold start a lot, especially when your work is complex. The reason is simple, the hard disk's continuous read and write speed is very fast, and random reading and writing ability is poor. From cold boot to working state hard drive reads DLLs everywhere, loads software everywhere, downloads documents everywhere ... From hibernation, the data is restored to memory from the continuous space on the hard disk, so it is very fast. Still, for example, in section 2.3, 2g ram will not cost more than 60 seconds to recover from hibernation, including power-on self-test and password input.

　　3. On component loss and energy issues

This is the focus of the second major debate, in fact there are a lot of misunderstanding, in fact, as long as a little bit of learning electronics, the truth is easy to understand. Hibernate and shutdown are not required any power, and the previous section has been explained that sleep is better than the shutdown of many, this section is the relationship between sleep and hibernation.

3.1 Static power consumption and rated power, in general, a chip to work, need a DC power supply, but also need a clock pulse input. CPU needs to input a certain frequency of the clock, this frequency is called FSB, and the CPU will automatically adjust the core frequency is equal to this FSB several times, is the octave. Memory also has its working frequency, what ddr667, ddr800 refers to is that the memory working frequency of 333MHz and 400MHz, because the DDR is in the clock rising along and down along a separate data read and write, so its clock frequency is its data frequency half. There is a concept is very important, in the system power configuration, said to save energy to shut down a device, actually refers to the shutdown of the device clock control, DC power is not cut off. The power consumption of a chip in the case of a DC connection without a clock is called the static power consumption of the chip, which is very small and is completely negligible compared to its rated power (dynamic power consumption).

3.2 Sleep state of power consumption, sleep state, in general, in addition to the memory of other devices, DC power is cut off, if the USB wake up function, then the USB is on the electricity. In this case, the actual power consumption is only the static power of memory, in fact, this is very small. The general notebook battery, if only online processing documents and so on, about 3 hours. But for sleep, the last time I slept 2 and a half days, I recovered to see 78% of the electricity. 3 hours of battery, 50 hours only used 20%, the difference is this.

3.3 Component loss problem, this is actually similar to the above, the loss of chip components are mainly in the clock work, in the static loss can also be negligible. As for the sleep and cold start hard disk loss comparison, I do not need to say, to listen to the hard disk sound and duration of the difference.

　　4. My Views and recommendations

At the beginning of the article I showed my opinion, now is to consider how to choose the relationship between dormancy and sleep. The simple truth is that the time to leave is too long to sleep, not too long. Demarcation line where, my experience is 24 hours, if the 24 hours to use the computer, sleep it, otherwise sleep, the scale can be based on their own experience to grasp. Like the kind of temporary leave (eat, sleep) is the most suitable for sleep pb54

4.1 For mixed sleep, the desktop is still recommended, in order to prevent accidental occurrence. Opening a mixed sleep only affects the time to sleep, and recovery time is unaffected. There is no need to open the notebook.

4.2 Power Plan, this is very important, it is strongly recommended that everyone should be based on the circumstances of each individual items, such as the time to turn off the monitor, the time to sleep and the time to go to sleep. Also have the function of each button to set up well, my habit (for reference only) is: For notebooks, cover is sleep, Start menu that button is also sleep, the power button on the machine is dormant; for desktops, the Start menu is sleep, and the power button on the host is dormant; As for shutdown and reboot, the odds are minimal, Point from the Shutdown menu next to the start.