It sounds like your confusing job steps and tasks. For an MPI program,
tasks and MPI ranks are the same thing. A slurm job has multiple steps.
A single job step could have only 1 task, while another step in the same
job can use 1,000 tasks. When looking at the amount of memory for a
job, the important number is the largest value of MaxRSS for all the job
steps. Why this important? Because if you don't request at least this
much with your --mem specification, your job may fail.
Based on your definition, of aveRSS (I didn't go back and check the
documentation myself), it sounds like you're doing unnecessary math,
since I'm sure Slurm sums up the individual task max. RSS values for
each task to get MaxRSS, and then divides that by the number of tasks to
get the AveRSS.
What you want is the MaxRSS for the job step with the largest value of
MaxRSS. For example, here's a parallel job I ran earlier today:
$ sacct -u pbisbal -o jobid,jobname,MaxRSS,AveRSS
JobID JobName MaxRSS AveRSS
------------ ---------- ---------- ----------
1100800 mcnp_test
1100800.bat+ batch 20999632K 20999632K
1100800.ext+ extern 1060K 964K
1100800.0 orted 24014384K 9238477482
The real "memory" for this entire job would be 24014384K
Prentice
On 3/9/21 3:41 AM, xiaojingh...@163.com wrote:
Hi guys,
I would like to calculate the CPU efficiency and Memory efficiency of slurm
jobs.
I am having difficulty calculating the real “memory” a job use.
According to slurm, “maxRSS” means "Maximum resident set size of all tasks in job”.
If so, how can I get the memory used by a single job? As far as I am concerned, if I
need to know the memory used by a single job/jobstep, I need to sum up the memory used
for each task. So I think I should use the “aveRSS” field which gives the "average
resident set size of all tasks in job”. If I multiply the “aveRSS” with “task”, I should
get the real memory a job/jobstep used.
But I studied the code of the “seff” command and it claims to be equivalent to "sacct
-P -n -a --format
JobID,User,Group,State,Cluster,AllocCPUS,REQMEM,TotalCPU,Elapsed,MaxRSS,ExitCode,NNodes,NTasks
-j <job_id>”, which means I should use “maxRSS”.
Can anyone give me some explanation on that?
Very grateful for any help.
Thank you!
Regards,
Xiaojing
