CODEWITHSUNDEEP
c++cgettimeofday
John
John

Reputation: 73

What is the unit of gettimeofday()?

I've a program to calculate the latency of an object in a pub-sub model. I've used the following function for timestamp:

uint64_t GetTimeStamp() {
    struct timeval tv;
    gettimeofday(&tv,NULL);
    return tv.tv_sec*(uint64_t)1000000+tv.tv_usec;
}

The latency is measured as timestamp difference in publisher and subscriber. So, I'm concerned about the unit of the latency measured. Is it in seconds or microseconds??

Upvotes: 5

Views: 16179

Answers (2)

Karthikeyan
Karthikeyan

Reputation: 990

The timeval structure has tv_sec, which gives you the absolute value for the seconds, and tv_usec, which gives you the remaining fraction in micro seconds.

So, you could get the resolution in micro seconds.

For more information, http://www.gnu.org/software/libc/manual/html_node/Elapsed-Time.html

Upvotes: 8

lulyon
lulyon

Reputation: 7225

tv.tv_sec gives the second count, tv.tv_usec gives the remaining microsecond count.

For gettimeofday() principle and its accuracy:

How is the microsecond time of linux gettimeofday() obtained and what is its accuracy?

Is gettimeofday() guaranteed to be of microsecond resolution?

Upvotes: 4

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