Post as a guest Name. BB code is On. Can you suggest me some function to measure the start time and end time so that I can find the difference between both. Zimbabao 7, 2 23 Measure Time in Linux with Time Base.

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Start Free Trial No credit card required. Lots of stuff may make sense on a 16GB machine which doesn’t make sense on a 4MB machine. This has to do with me wanting to make sure I go to gettimeofeay early.

How do I get the current hour? Back when Linux was new, wasting 1MB to double in-kernel performance would’ve been ridicolous.

Of course it’s possible that the effect would be getitmeofday dramatic on x86 hardware running Linux but it’s still an option to consider. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

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The time and gettimeofday System Calls. If you assume the large machine has 10 times as many processes, you’ve still only wasted 0. I’m writing a kernel module that checks to see if the time is between two specified hours, and gettimeofvay input if it is.

c – How to get current hour (time of day) in linux kernel space – Stack Overflow

If you’d like to contribute content, let us know. Hi, I have written one kernel level program and I want to measure the execution time of my kernel function inside this program. The system call would still exist for legacy support Stack Overflow works best with JavaScript enabled.


ANd more over to measure acurate time in user space, you should always use “struct timeval”. Here is an example program that shows usage: Linux – Software This forum is for Software issues. Comparing Linux and Minix While gettimeofday should be one of the simplest system calls in the universe and uname should be another Gehtimeofday a gettimeogday installing a new program?

The time system call is superseded by gettimeofdaybut it is still included in Linux for backward compatibility. Click Here to receive this Complete Guide absolutely free.

gettimeofday() — user-space vs. system call

Post Your Answer Discard By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies. By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. May I just say, such a kernel module does not sound pleasant to debug!

I’m pretty sure that you aren’t supposed to use floating point calculations in kernel code, as the kernel doesn’t keep track of the FPU’s state when the kernel is running code. The code in user space is as below.


Email Required, but never shown. The code on the vsyscall page which normally runs SYSENTER could spot that the syscall being invoked is gettimeofday and copy out the appropriate value from elsewhere in the vsyscall page without ever transitioning to kernel mode.

Because clock can’t give accracy in msec. I have no access to the usual time functions in the standard library because I am in kernel space. System Calls Related to Timing Measurements. Please visit this page to clear all LQ-related cookies. This book contains many real life examples derived from the author’s experience as a Linux system and network administrator, trainer and consultant.

Posted Aug 23, Introduction to Linux – A Hands on Guide This guide was created as an overview of the Linux Operating System, geared toward new users as an exploration tour and getting started guide, with exercises at the end of each chapter. Zimbabao 7, 2 23