Thoughts from the EPS Windows Server Performance Team
It's Day Two of our series of Windows Server 2008 posts. Only twenty-five more days to go till the big launch. Today's topics are Startup Processes and Delayed Automatic Start for System Services.
In previous versions of Windows, during system boot, the Session Manager process (SMSS.EXE) would start the Client-Server Runtime Subsystem (CSRSS.EXE), and the logon process (WINLOGON.EXE). The Winlogon process would then launch the Local Security Authority Subsystem Service, better known as LSASS.EXE and the Service Control Manager (SERVICES.EXE). The user logged into the console would be logged into Session 0, which is the shared session used by system processes. One security risk was that if a poorly written Windows service running in Session 0 displayed a user interface on the interactive console, malware could attack the window using windows messages and possibly gain administrative privileges to the system.
To address these potential issues, several system processes were redesigned for Windows Vista and Windows Server 2008. SMSS.EXE is still the first user-mode process created during the boot process as in previous versions. The change is that now SMSS.EXE launches a second instance of itself to configure Session 0, which is dedicated to system processes. The instance of SMSS.EXE dedicated to Session 0 launches the Windows Startup Application (WININIT.EXE) as well as an instance of CSRSS.EXE for Session 0, after which it exits. WININIT.EXE continues the startup process by starting SERVICES.EXE and LSASS.EXE as well as a new process, the Local Session Manager (LSM.EXE) which manages Terminal Server connections for the machine.
In parallel with the creation of Session 0, a Console session is also initialized. The initial instance of SMSS.EXE creates a new instance of itself to configure the Console session - just as it did with Session 0. The new instance of SMSS.EXE starts an instance of CSRSS.EXE and WINLOGON.EXE for the Console session in preparation for user logon. WINLOGON.EXE then launches the Logon User Interface Host (LOGONUI.EXE) which presents the Windows Security screen prompting the user to press CTRL+ALT+DELETE to log on.
When a user attempts to log on to the system, the initial instance of SMSS.EXE creates a new instance of itself to configure the new session just as it did for Session 0 and the Console session. This new instance of SMSS.EXE starts a CSRSS.EXE process and a WINLOGON.EXE process for the new session. WINLOGON.EXE starts LOGONUI.EXE to present the logon screen to the user. This may seem as though it would cause unnecessary overhead on a system, and on a client system, it does not provide any noticeable advantage. However, on Windows Server 2008 Terminal Server systems, multiple instances of SMSS.EXE can run concurrently - providing faster logons for multiple users.
Let's move on to take a quick look at another new feature of Windows Vista and Windows Server 2008 - Delayed Automatic Start for System Services. To address the problem of the growing number of services set to start automatically and the subsequent negative impact on boot performance, there is a new start type for services that do not need to start early in the boot process - the Delayed start. This allows a service to still start automatically, but with the added advantage that boot performance is improved. Services set to start as Delayed will start shortly after boot.
So how does this work? The Service Control Manager starts services that are configured for delayed automatic start after all of the automatic-start threads have finished starting. The Service Control manager also sets the priority of the initial thread for these delayed services to THREAD_PRIORITY_LOWEST. This causes all of the disk I/O performed by the thread to be very low priority. Once a service finishes initializing, the priority is set back to normal by the Service Control Manager. The combination of the delayed start, low CPU and memory priority, as well as the background disk priority greatly reduce the interference with the user's logon. Many Windows services, including the Background Intelligent Transfer Service (BITS), Windows Update Client, and Windows Media Center, use this new start type to help improve logon performance after a system boot. To configure a service for delayed automatic start, you can create a REG_DWORD value called DelayedAutoStart in the service's configuration registry key under HKLM\SYSTEM\CurrentControlSet\Services.
That brings us to the end of Day Two. Tomorrow we will take a look at Service Hardening, which is quite a lengthy topic. Until next time ...
- CC Hameed
PingBack from http://www.ditii.com/2008/02/02/windows-server-2008-startup-processes-and-delayed-automatic-start/
While the efforts to speed up logon using delayed start are nice, the rewriting of the servicing stack which for no reason seems to require "configuration of updates" completely slows down logon on Vista and later OSes.
I have a service that uses signed dlls. on start up the service does not start automatically. i marked the service configuration as DelayedAutoStart but in vain. when i deploy the service without signed dlls the service run correctly. help me what can be the problem??
Can you tell more details about how to
"To configure a service for delayed automatic start, you can create a REG_DWORD value called DelayedAutoStart in the service's configuration registry key under HKLM\SYSTEM\CurrentControlSet\Services."?
What is the value should be?
To set a service to delayed start, just add the DelayedAutoStart RED_DWORD entry and give it a value of 1.
Does Windows have a pop-up window at start-up that will show what is loading in real time?
Hi That Guy,
Sorry, but nothing like that exists. The best you can do is the equivilent of the old /SOS boot.ini switch, which is what causes the list of loading drivers to scroll by when you boot up into Safe Mode. You can enable this in Windows Server 2008 by using Msconfig.exe and enabling 'OS Boot Information' on the Boot tab. However, I don't think this is what you are looking for. To view what services are doing in real time would require another service or process to explicitly monitor and display this information in the user session.
Can this be configured in windowsXP pro registry.
Great post. It was helpful for me in solving a problem when installing NAS service coming from Dynamics NAV 2009 SP1 product CD. Thanks CC !
I'm trying to look for the group policy setting to set this startup type back to just Automatic instead of Automatic (Delayed Start).
I tried doing this locally but obviously our group policy keeps reverting it back to the delayed start and I don't know where to find the group policy setting for this. Do I need to download a new .adm file?