I am running a Linux 2.6.24.7-rt21 Kernel on our HW. This HW contains a number of IO-Ports, and the drivers for these IO-Ports are designed in a way, that various ioctl() function provide the interface to these Ports. Now, i recognized, that processes, which are using such ioctl()'s, absolutely do not run in realtime (regardless on the priority). If i cat a huge file to a /dev/ttyX device, the process jitters for many milliseconds. This does NOT happen, if i modify the driver and the user space process to access IO's via read() and write() instead of ioctl()'s. My question is: Is it a known and intended behaviour, that ioctl()'s ruin realtime behaviour, and that IO's should only be accessed via read() and write() ? I didnt find any documentation, which would advice me not to use ioctl() in realtime applications. -- Mit freundlichen Gruessen / Best regards Claus Gindhart SW R&D Kontron Modular Computers phone :++49 (0)8341-803-374 mailto:claus.gindhart@xxxxxxxxxxxxxxxxxxx http://www.kontron.com -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
