问题
What is the big deal with HTTP.SYS in IIS 7?
From what I understand, it is low level which is good for security. Why?
There is no context switching which could be expensive. Why?
Please explain.
Thanks!
回答1:
The benefits are already well documented,
http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/a2a45c42-38bc-464c-a097-d7a202092a54.mspx?mfr=true
By using HTTP.sys to process requests, IIS 6.0 delivers the following performance enhancements:
- Kernel-mode caching. Requests for cached responses are served without switching to user mode.
- Kernel-mode request queuing. Requests cause less overhead in context switching, because the kernel forwards requests directly to the correct worker process. If no worker process is available to accept a request, the kernel-mode request queue holds the request until a worker process picks it up.
Using HTTP.sys and the new WWW service architecture provides the following benefits:
- When a worker process fails, service is not interrupted; the failure is undetectable by the user because the kernel queues the requests while the WWW service starts a new worker process for that application pool.
- Requests are processed faster because they are routed directly from the kernel to the appropriate user-mode worker process instead of being routed between two user-mode processes.
http://learn.iis.net/page.aspx/101/introduction-to-iis-7-architecture/
HTTP.sys provides the following benefits:
- Kernel-mode caching. Requests for cached responses are served without switching to user mode.
- Kernel-mode request queuing. Requests cause less overhead in context switching because the kernel forwards requests directly to the correct worker process. If no worker process is available to accept a request, the kernel-mode request queue holds the request until a worker process picks it up.
- Request pre-processing and security filtering.
来源：https://stackoverflow.com/questions/3153069/http-sys-kernel-mode-driver