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

  • Salesforce has been recognized by Gartner as a leader in this report for three years in a row. This graphic was published by Gartner, Inc. as part of a larger research document and should be evaluated in the context of the entire document. The Gartner document is available upon request from Salesforce.com. Gartner does not endorse any vendor, product or service depicted in its research publications, and does not advise technology users to select only those vendors with the highest ratings. Gartner research …

  • You've managed to piece together the "DREAM TEAM." Your tech staff works like a well-oiled machine, keeping your company humming and thriving. And then it happens: dissension. For whatever reason, your employees have grown unhappy and you find out they're searching for new employment or losing productivity. What did you do wrong? Did you hire the wrong people? Did your company push them away? Or is it a combination of numerous factors? Read this white paper to learn how to build an environment that fosters …

Most Popular Programming Stories

More for Developers

RSS Feeds

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