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

  • On-demand Event Event Date: March 19, 2015 The 2015 Enterprise Mobile Application Survey asked 250 mobility professionals what their biggest mobile challenges are, how many employees they are equipping with mobile apps, and their methods for driving value with mobility. Join Dan Woods, Editor and CTO of CITO Research, and Alan Murray, SVP of Products at Apperian, as they break down the results of this survey and discuss how enterprises are using mobile application management and private app stores to …

  • Live Event Date: May 11, 2015 @ 1:00 p.m. ET / 10:00 a.m. PT One of the languages that have always been supported with the Intel® RealSense™ SDK (Software Developer Kit) is JavaScript, specifically so that web-enabled apps could be created. Come hear from Intel Expert Bob Duffy as he reviews his own little "space shooting" game where the orientation of your face controls the aiming reticle to help teach developers how to write apps and games in JavaScript that can use facial and gesture …

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