Articles Written by John Gulbrandsen

System Call Optimization with the SYSENTER Instruction

Windows NT calls system services by using an "int 2e" software interrupt. The "int 2e" instruction uses both an interrupt gate and a code segment descriptor to find the interrupt service routine (KiSystemService) which services the "int 2e" software interrupt. Since the CPU will have to load one interrupt gate and one segment descriptor from memory in order to know what interrupt service routine to call, significant overhead is involved in making an "int 2e" system call. The SYSENTER instruction drastically reduces this overhead.

How Do Windows NT System Calls REALLY Work?

Learn about the exact mechanism that Windows NT uses when switching to kernel mode to execute a system service. The description is for an x86-compatible CPU running in protected mode. Other platforms supported by Windows NT will have a similar mechanism for switching to kernel mode.

Top White Papers and Webcasts

  • Featuring Art Schoeller, VP and Principal Analyst, Forrester Research Wednesday, August 31, 2016 10:00 AM PT | 1 PM ET If Agility Is Essential to Your Business Survival--Now's the Time to Start the Move to Cloud! The maturity of cloud platforms has given organizations new confidence in moving mission-critical systems to the cloud, to gain agility, scale and realize cost benefits in the process. How can your company achieve these benefits, and what steps are necessary to begin your contact center's …

  • Microsoft® Office 365 is a top choice for enterprises that want a cloud-based suite of productivity/ collaboration applications. With Office 365, you get access to Microsoft™ Office solutions practically anytime, anywhere, on virtually any device. It's a great option for current Microsoft users who can now build on their experience with Microsoft™ solutions while enjoying the flexibility of a cloud-based delivery. But even organizations with no previous investment in Microsoft will find that …

Most Popular Programming Stories

More for Developers

RSS Feeds

Thanks for your registration, follow us on our social networks to keep up-to-date