Mar 19, 2011 · Man Pages say - The time returned by gettimeofday() is affected by discontinuous jumps in the system time (e.g., if the system administrator manually changes the system time). If you need a monotonically increasing clock, see clock_gettime(2).

Syscalls generally create a lot of overhead, and given the abundance of gettimeofday() calls, one would prefer not to use a syscall. To that end, Linux kernel may map one or two special areas into each program, called vdso and vsyscall. Your implementation of gettimeofday() seems to be using vsyscall: mov $0xffffffffff600000,%rax

The gettimeofday() function retrieves the current Coordinated Universal Time (UTC) and places it in the timeval structure pointed to by tp. If tzp is not NULL, the time zone information is returned in the time zone structure pointed to by tzp .

Jan 1, 1970 · The gettimeofday() function obtains the current time, expressed as seconds and microseconds since 00:00:00 Coordinated Universal Time (UTC), January 1, 1970, and stores it in the timeval structure pointed to by tp. Special behavior for _ALL_SOURCE: The gettimeofday() function has two prototypes. Which one is used depends on whether or not you ...

Jan 11, 2023 · Does anyone know an equivalent function of the gettimeofday() function in Windows environment? I am comparing a code execution time in Linux vs Windows. I am using MS Visual Studio 2010 and it keeps saying, identifier "gettimeofday" is undefined.

Apr 4, 2015 · While using the TSC is a reasonable idea, modern Linux already has a userspace TSC-based gettimeofday - where possible, the vdso will pull in an implementation of gettimeofday that applies an offset (read from a shared kernel-user memory segment) to rdtsc's value, thus computing the time of day without entering the kernel. However, some CPU ...

現行格林威治時間及現行時區會與 gettimeofday 子常式一起顯示，並與 settimeofday 子常式一起設定。 時間以秒及微秒表示，自 1970 年 1 月 1 日午夜 (0 小時) 以來。 系統時鐘的解析度取決於硬體，時間可以持續更新或以「刻度」表示。

gettimeofday() 関数は、 協定世界時 (UTC) 1970 年 1 月 1 日 00:00:00 からの秒数とマイクロ秒数 で表した現在の時刻を取得し、それを tp が指す timeval 構造体へ格納します。 _ALL_SOURCE の特殊な動作: gettimeofday() 関数には 2 つのプロトタイプがあります。 1 つは ...

Feb 24, 2014 · I need to use gettimeofday to measure time differences in microsecond resolution using this function. I know this is not the best function, but I want to understand why. In this question AndrewStone says there'll be a problem twice a yea, I don't understand why would there be a problem if we're just counting microseconds from epoch.

Sep 8, 2021 · gettimeofday(2) as been declared obsolete in behalf of clock_gettime(2) that has better resolution than the older one (It uses nanosecond resolution) Precission is another issue (different) in that it depends on how the hardware allows you to get a timestamp and how the operating system implements it.