CODEWITHSUNDEEP
capimemoryhpcslurm
mac13k
mac13k

Reputation: 2663

How to get memory usage information using Slurm C API?

I am looking for the way to get per job memory usage information from Slurm using C API, namely memory used and memory reserved. I thought I could get such stats by calling slurm_load_jobs(…), but looking at job_step_info_t type definition I could not see any relevant fields. Perhaps there could be something in job_resrcs, but it is an opaque data type and I have no idea how to use it. Or is there another API call that would give me detailed memory usage info? Please advise.

Upvotes: 2

Views: 589

Answers (1)

mac13k
mac13k

Reputation: 2663

This question was partially answered in this SO thread where the focus was only on the compiler errors. The missing portion of code was the loop through memory_allocated and memory_used arrays sized according to the number of hosts the job was dispatched to:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "slurm/slurm.h"
#include "slurm/slurm_errno.h"


struct job_resources {
        bitstr_t *core_bitmap;
        bitstr_t *core_bitmap_used;
        uint32_t  cpu_array_cnt;
        uint16_t *cpu_array_value;
        uint32_t *cpu_array_reps;
        uint16_t *cpus;
        uint16_t *cpus_used;
        uint16_t *cores_per_socket;
        uint64_t *memory_allocated;
        uint64_t *memory_used;
        uint32_t  nhosts;
        bitstr_t *node_bitmap;
        uint32_t  node_req;
        char     *nodes;
        uint32_t  ncpus;
        uint32_t *sock_core_rep_count;
        uint16_t *sockets_per_node;
        uint16_t *tasks_per_node;
        uint8_t   whole_node;

};

int main(int argc, char** argv)
{
        int i, j, slurm_err;
        uint64_t mem_alloc, mem_used;
        job_info_msg_t *jobs;

        /* Load job info from Slurm */
        slurm_err = slurm_load_jobs((time_t) NULL, &jobs, SHOW_DETAIL);
        printf("job_id,cluster,partition,user_id,name,job_state,mem_allocated,mem_used\n");
        /* Print jobs info to the file in CSV format */
        for (i = 0; i < jobs->record_count; i++)
        {
                mem_alloc = 0;
                mem_used = 0;
                for (j = 0; j < jobs->job_array[i].job_resrcs->nhosts; j++)
                {
                        mem_alloc += jobs->job_array[i].job_resrcs->memory_allocated[j];
                        mem_used  += jobs->job_array[i].job_resrcs->memory_used[0];
                }
                printf("%d,%s,%s,%d,%s,%d,%d,%d\n",
                        jobs->job_array[i].job_id,
                        jobs->job_array[i].cluster,
                        jobs->job_array[i].partition,
                        jobs->job_array[i].user_id,
                        jobs->job_array[i].name,
                        jobs->job_array[i].job_state,
                        mem_alloc,
                        mem_used
                );
        }
        slurm_free_job_info_msg(jobs);
        return 0;
}

This program compiles and runs without errors. One thing I noticed though is that mem_used is either 0 or equal to mem_alloc which sometimes differs from what I get from the sstat command. I will have to investigate this further...

Upvotes: 1

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