@Maryem Mary,
You can use the mapreduce command line tool to get the execution time for each job. Use the below command to get all the stats of a job
mapred job -status {job-id}
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To get the execution time, use
mapred job -status {job_id} | grep "CPU time"
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If you have YARN application Id ,then replace 'application_xxx' with 'job_xxx' to get the mapreduce job id.
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If you have written the Mapreduce application, then you can have custom counters as well to print extra information. See the example in the link
https://acadgild.com/blog/counters-in-mapreduce.
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Please "Accept" the answer if this helps.