Improving "Cold Boot" Time for System Manufacturers

BIOS POST - the time for the power-on self test (POST)

Pre-Logon - the time from BIOS POST handoff to the Windows Logon screen

Post-Logon - the time from closing the Logon screen to a usable Start menu

Do not clear memory if there's no memory error detection.
Windows Me and Windows 2000 do not expect memory to be cleared before loading the operating system on PCs shipped without memory error detection or correction hardware (ECC/parity).

Remove advertisements from expansion ROMs.
(This is commonly an issue with video BIOS. We have also seen this with network adapters.)

Use smaller centered OEM logo screens during POST rather than large bitmaps. Testing has shown an improvement of up to 2 seconds in POST related to the size of the OEM logo bitmap.

If the PC does not support ATA expansion past a single hard drive and CD/DVD, configure the BIOS to not look for other devices on the primary and secondary ATA channels.

Connect the hard disk and CD-ROM/DVD to the primary ATA controller as Device 0 and Device 1.
Testing has shown that doing this does not degrade system/multimedia performance on systems with 64 MB of RAM or more.

Program ATA transfers for the maximum rate.
Many BIOSes focus only on loading the operating system, and then the operating system driver enables maximum transfer mode/DMA after it loads. Several seconds can be saved if the BIOS enables higher transfer rates. This is particularly important when resuming from hibernate and during the early portions of a cold boot.

Use a legacy-free BIOS.

This will eliminate unnecessary delays such as ISA Plug and Play.

Use Simple Boot Flag so that the boot order begins with hard drive for the normal boot scenario. On systems with CD-ROM boot order set as first on normal boot, if a disc is in the tray, the CD-ROM must be spun up to determine whether the CD in the tray is bootable. This can delay boot by several seconds.

Windows Me has full support for the Simple Boot Flag, which can help improve BIOS POST time for both cold boot and resume from hibernate. By using Simple Boot Flag, time-consuming configuration and test procedures in the BIOS can be isolated to a failed boot path. The normal boot path can eliminate these processes, dramatically speeding up BIOS POST.

For cold boot, Windows clears the Simple Boot flag during the VMM_INIT portion of boot.

For a resume from hibernate, Windows Me clears the Simple Boot flag after reading the hibernate file but before the display is turned back on (Implemented after Windows Me Beta 3).

Use the PNP Enumeration tool to measure device enumeration and driver load times. (See "PNP Enumeration Tool and Boot Time Measurement" at the end of this article.)

See Table 1 for guidelines in choosing fast hardware. These are actual times measured in the Windows Me performance lab on real hardware. Use these numbers as a starting point as you work with your suppliers to evaluate new solutions.

This chart is a guide, not a definitive set of numbers for good and poor hardware. The best way to determine the quality of driver load times for a system is to compare that system's device/driver times to that of other similar devices on the market.

You can use the PNP Enumeration tool to isolate slow devices that may be improved and also to pick the faster ones.

Table 1. Boot Time Reference for Hardware Components

Fix drivers to load faster

Make sure DMA is turned on for the hard disk. This can improve boot performance by as much as 2 seconds.

Defrag the system images before shipping them to users.

Ensure the BIOS is programmed for maximum supported ATA transfer rates. We have seen some BIOSes doing 16-bit transfers rather than 32-bit transfers and using PIO Mode 0 rather than higher modes that yield better performance. Supporting maximum transfer rates will greatly improve resume-from-hibernate performance in reading the hibernate file.

Choose hard drives for fast spin-up. There is a delicate tradeoff to make for spindle rate versus spin-up rate. The higher the spindle rate, typically the slower the spin-up. However, within a given spindle rate, screen for the best spin-up speed. Higher spin-up rates may slow BIOS POST while delivering far faster Pre-Logon and Post-Logon times. Using a 7200 RPM hard disk can improve overall boot time dramatically across all three phases.

Use as much built-in Windows functionality as possible. For example, use the Windows built-in Task Scheduler for reminders, anti-virus programs, scheduled anti-virus pattern file updates, and so on.

Don't add extra schedulers to the system.

Use standard HID key mappings on keyboards. Adding extra keyboard hook programs have been shown to slow boot time by as much as 4 seconds while consuming as much as 5% of USER resources. Windows Me has built-in support for a large variety of "special" keyboard buttons for launching web browsers, volume control, CD controls, and so on. (See http://www.microsoft.com/whdc/device/input/default.mspx)

Leverage Windows Me PC-Health support services such as Auto-Update, Help Center, and System Restore. These services have been tuned to minimize effect on boot and working set.

Only load what is critical for the end user. Consider delayed loading rather than loading everything when the system starts.

Make sure that all items in the Run registry key point to valid executable files on the disk. We've seen pre-load configurations that attempt to detect all cards that might optionally ship with a PC. This leaves dangling registry keys that delay boot by searching and then failing to find files because the related hardware was not shipped on the system.

Run items at lower thread priority to minimize the load on the system.

Defrag images before shipping them to users.

Implementing a fast BIOS POST improves both cold boot and hibernate resume times.

Implementing a fast hard disk (spin-up and throughput) improves hibernate resume time.

Implementing BIOS programming for highest speed ATA transfers improves hibernate resume time.

Implementing fast loading drivers improves resume times, because of the Plug and Play enumeration performed by Windows when resuming from hibernate.

No real mode processing. Windows Me does not process Autoexec.bat or Config.sys during the boot process.

Some PCs load real-mode CD-ROM and sound card drivers that expend as much as 20 seconds in boot time. Such drivers are not needed on systems running Windows Me.

Improved registry structure:

The registry is now broken up into 3 files (User.dat, System.dat, Classes.dat) to make loading the registry more efficient. Windows Me loads only the portions of the registry that are required during boot.

Improved Plug and Play enumeration. Windows Me is less serialized than Windows 98 when detecting devices during the boot process.

Merged real mode drivers in Io.sys. Services such as HIMEM and SMARTDRV, which are separate files in Windows 98 that must be loaded during boot, are now built into the Windows Me Io.sys file. This improves read performance of the hard disk during boot. Io.sys is compressed, which reduces disk size and makes it faster to load.

Task Scheduler modified as a background system service. Windows 98 included a system tray icon for switching off this service. Windows Me provides the scheduler as a system service, which can be used to schedule important tasks for the user (maintenance, anti-virus pattern reminders, and so on). Windows Me eliminates the tray icon for the Task Scheduler, making it less visible to the end user and therefore more likely to remain running.

Media sense and TCP/IP. Technology in the Windows Me TCP/IP stack (also available on Windows 2000) allows for faster boot times in network scenarios when the DHCP server is unavailable or when a network cable isn't plugged into the network adapter. In Windows 95/98, boot time could increase up to 24 seconds while seeking a DHCP server. In Windows Me with media-sense aware drivers, boot time is improved dramatically.

Ensure the complete pre-loaded configuration is on the system.

Set the display to 800 x 600 x 16 bpp.

Set all actions for power schemes in power management to Never:

Configure network setup:

Turn on the Windows F8 boot menu:

Create batch file for Post-Logon times:

Add Timing.bat to the Run key in the system registry:

Monitors: Monitors have been observed to effect BIOS POST and Pre-Logon time.

ATA devices: ATA configuration has been observed to affect BIOS POST and Pre-Logon time.

Network environment: Testing on systems that include a network adapter should be done on a small private network. Network traffic can cause large deviations in measuring boot and resume from hibernate times.

Startup items: Lots of items loaded from the Run key and Startup group have been observed to cause very large deviations in Post-Logon times.

(C) means Config Handler (driver)

(E) means enumerator handler (an enumerator processing a message for a child)

(NEWDEVNODE) is the message sent to the devloader during Plug and Play enumeration