Measure execution time in C (for Linux and Windows)

Links related to the topic of measuring execution time:
stackoverflow.com/a/37920181
learn.microsoft.com/en-us/win...
Source code can be found here:
code-vault.net/lesson/7475a60...
===== Support us through our store =====
code-vault.net/shop
===== Check out our website =====
code-vault.net
===== Check out our Discord server =====
discord.code-vault.net

[@KFlorent13]

Oh you are back ! How exciting ;)

[@isaiasramirez2909]

great video!

[@NenieIri]

and what are you think about clock() function? In manual says "clock - determine processor time". Does it correct to use for measurement or not?

[@CodeVault]

On Linux, it's a good choice since it simply calls clock_gettime with the CPUTIME constant. On Windows it returns the wall clock and recommends us using what I showed in the video (learn.microsoft.com/en-us/cpp/c-runtime-library/reference/clock?view=msvc-170). Not sure about other platforms. I found it in my research and decided to not show it as it causes more confusion.

[@NenieIri]

@@CodeVault Thank you

[@mehregankbi]

now i don't know if it's the best way of doing this, but measuring the difference between a process' cpu time and wall time could be used to measure io boundedness of that process. (given that the CPU is not overloaded, so the amount of time the process spends in the ready queue is negligible compared to the amount of time that it stays in the waiting queue.

[@CodeVault]

That's a nice topic to research about. There are many instances where processes are slow due to IO operations and finding that out is quite useful. I might even make a video on this

[@michaelvanzyl9418]

Would the compiler not be clever enough to optimise out any operations done on x, if it’s never read from? (Or does that require an optimisation flag)

[@CodeVault]

Yes, it does optimize it away but only with -O2. By default it should be left alone

[@michaelvanzyl9418]

@@CodeVault ahh, makes sense.

[@markobrodanac4304]

Is this CPU time equal to sys or user time when measuring with time function in shell?

[@CodeVault]

In shell the time command is explained here: linux.die.net/man/1/time You do get real time and CPU user time

[@mritunjaykumar8332]

can you please create a video on EPOCH time, how to convert epoch time (in seconds) to actual time without using any inbuilt functions in c ?

[@CodeVault]

There is this video on the topic: code-vault.net/lesson/931c1634bae351f1ec660773c5001a5b Although it does use some standard functions. I noted down your question, maybe I will do a video on that if it's not too difficult (working with date and time is often complicated)

[@mritunjaykumar8332]

@@CodeVault Thank you for your awesome videos

[@akhilpandey1539]

My question is different from this topic... Can we find the maximum number of thread that we can create in a program?

[@CodeVault]

To find out you can simply use this command: cat /proc/sys/kernel/threads-max

[@msrinivas20]

Where can I get this compiler sir ? How can I install it. Please reply back the link. Tq

[@CodeVault]

gcc gcc.gnu.org/ can be found on most Linux distros and, for Windows I am just using MSVC in Visual Studio visualstudio.microsoft.com/

[@mba2ceo]

||=== Build: Debug in timeckick (compiler: GNU GCC Compiler) ===| C:\zzz-code\options\timeckick\main.cpp||In function 'int main(int, char**)':| C:\zzz-code\options\timeckick\main.cpp|8|error: aggregate 'main(int, char**)::timespec begin' has incomplete type and cannot be defined| C:\zzz-code\options\timeckick\main.cpp|9|error: 'TIME_UTC' was not declared in this scope| C:\zzz-code\options\timeckick\main.cpp|9|error: 'timespec_get' was not declared in this scope| C:\zzz-code\options\timeckick\main.cpp|22|error: aggregate 'main(int, char**)::timespec end' has incomplete type and cannot be defined| ||=== Build failed: 4 error(s), 0 warning(s) (0 minute(s), 0 second(s)) ===|

[@CodeVault]

Try using the code for Windows instead. You can find it here under main-vs.c: code-vault.net/lesson/7475a60f972f545c64ae6e5ab80007af