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digitalmars.D.learn - Measuring Execution time

reply "Clayton" <johnsjdsd gmail.com> writes:
How does one represent Duration in only Micro-seconds, or 
milliseconds. Trying to measure the execution time of an 
algorithm and I get "4 ms, 619 μs, and 8 hnsecs" , I want to sum 
all these and get total hnsecs or μs .

I would also  appreciate advise on  whether this is the best way 
to measure the execution time of an algorithm.



import std.datetime;
import std.stdio;

void algorithm( ){
	writeln("Hello!");
}
void main(){

         auto stattime = Clock.currTime();
	algorithm( );
	endttime = Clock.currTime();

	auto duration = endttime - stattime;

	writeln("Hello Duration ==> ", duration);

}
Jul 22 2015
next sibling parent reply "John Colvin" <john.loughran.colvin gmail.com> writes:
On Wednesday, 22 July 2015 at 09:23:36 UTC, Clayton wrote:
 How does one represent Duration in only Micro-seconds, or 
 milliseconds. Trying to measure the execution time of an 
 algorithm and I get "4 ms, 619 μs, and 8 hnsecs" , I want to 
 sum all these and get total hnsecs or μs .

 I would also  appreciate advise on  whether this is the best 
 way to measure the execution time of an algorithm.



 import std.datetime;
 import std.stdio;

 void algorithm( ){
 	writeln("Hello!");
 }
 void main(){

         auto stattime = Clock.currTime();
 	algorithm( );
 	endttime = Clock.currTime();

 	auto duration = endttime - stattime;

 	writeln("Hello Duration ==> ", duration);

 }
The normal way of doing this would be using std.datetime.StopWatch: StopWatch sw; sw.start(); algorithm(); long exec_ms = sw.peek().msecs;
Jul 22 2015
next sibling parent "Clayton" <johnsjdsd gmail.com> writes:
On Wednesday, 22 July 2015 at 09:32:15 UTC, John Colvin wrote:
 On Wednesday, 22 July 2015 at 09:23:36 UTC, Clayton wrote:
 [...]
The normal way of doing this would be using std.datetime.StopWatch: StopWatch sw; sw.start(); algorithm(); long exec_ms = sw.peek().msecs;
Much appreciated, that works well John . Learning goes on... thanks again
Jul 22 2015
prev sibling parent reply "Clayton" <johnsjdsd gmail.com> writes:
On Wednesday, 22 July 2015 at 09:32:15 UTC, John Colvin wrote:
 On Wednesday, 22 July 2015 at 09:23:36 UTC, Clayton wrote:
 [...]
The normal way of doing this would be using std.datetime.StopWatch: StopWatch sw; sw.start(); algorithm(); long exec_ms = sw.peek().msecs;
Am wondering how possible is to restrict that all algorithms get run on a specific core( e.g. CPU 0 ) since I wanted my test run on the same environment.
Jul 23 2015
parent reply Yazan D <invalid email.com> writes:
On Thu, 23 Jul 2015 16:43:01 +0000, Clayton wrote:

 On Wednesday, 22 July 2015 at 09:32:15 UTC, John Colvin wrote:
 On Wednesday, 22 July 2015 at 09:23:36 UTC, Clayton wrote:
 [...]
The normal way of doing this would be using std.datetime.StopWatch: StopWatch sw; sw.start(); algorithm(); long exec_ms = sw.peek().msecs;
Am wondering how possible is to restrict that all algorithms get run on a specific core( e.g. CPU 0 ) since I wanted my test run on the same environment.
If you are using Linux, you can use `taskset`. Example: `taskset -c 0 ./program`. This will run your program on the first CPU only.
Jul 24 2015
parent Yazan D <invalid email.com> writes:
There is also http://linux.die.net/man/2/sched_setaffinity if you want to 
do it programmatically.
Jul 24 2015
prev sibling parent reply Steven Schveighoffer <schveiguy yahoo.com> writes:
On 7/22/15 5:23 AM, Clayton wrote:
 How does one represent Duration in only Micro-seconds, or milliseconds.
 Trying to measure the execution time of an algorithm and I get "4 ms,
 619 μs, and 8 hnsecs" , I want to sum all these and get total hnsecs or
 μs .

 I would also  appreciate advise on  whether this is the best way to
 measure the execution time of an algorithm.



 import std.datetime;
 import std.stdio;

 void algorithm( ){
      writeln("Hello!");
 }
 void main(){

          auto stattime = Clock.currTime();
      algorithm( );
      endttime = Clock.currTime();

      auto duration = endttime - stattime;

      writeln("Hello Duration ==> ", duration);

 }
I know John identified Stopwatch, but just an FYI, Duration has the method total: http://dlang.org/phobos/core_time.html#.Duration.total I think doing: writeln("Hello Duration ==> ", duration.total!"usecs"); would also work. -Steve
Jul 23 2015
parent Jonathan M Davis via Digitalmars-d-learn writes:
On Thursday, July 23, 2015 13:59:11 Steven Schveighoffer via
Digitalmars-d-learn wrote:
 On 7/22/15 5:23 AM, Clayton wrote:
 How does one represent Duration in only Micro-seconds, or milliseconds.
 Trying to measure the execution time of an algorithm and I get "4 ms,
 619 μs, and 8 hnsecs" , I want to sum all these and get total hnsecs or
 μs .

 I would also  appreciate advise on  whether this is the best way to
 measure the execution time of an algorithm.



 import std.datetime;
 import std.stdio;

 void algorithm( ){
      writeln("Hello!");
 }
 void main(){

          auto stattime = Clock.currTime();
      algorithm( );
      endttime = Clock.currTime();

      auto duration = endttime - stattime;

      writeln("Hello Duration ==> ", duration);

 }
I know John identified Stopwatch, but just an FYI, Duration has the method total: http://dlang.org/phobos/core_time.html#.Duration.total I think doing: writeln("Hello Duration ==> ", duration.total!"usecs"); would also work.
Yes, you could do that, but doing timing with the realtime clock is fundamentally wrong, because the clock can change on you while you're timing. That's why using a monotonic clock is better, since it's guaranteed to never move backwards. Unfortunately, while StopWatch does use a monotonic clock, it currently does that by using TickDuration for that rather than MonoTime, so its result is a TickDuration rather than a Duration, so it's a bit harder to use than would be nice, but it is more correct to use StopWatch than to subtract SysTimes. Alternatively, you could just use MonoTime directly. e.g. auto startTime = MonoTime.currTime; // do stuff auto endTime = MonoTime.currTime; audo duration = endTime - startTime; writeln("Hello Duration ==> ", duration.total!"usecs"); in which case you get a Duration just like with subtract SysTimes, and the suggestion of using total works just fine. I need to put together replacements for the benchmarking functions in std.datetime (probably in std.benchmark) which use MonoTime and Duration rather than TickDuration so that we can deprecate the ones in std.datetime which use TickDuration (and deprecate TickDuration itself). - Jonathan M Davis
Jul 23 2015