C/C++: Comparing the performance of syslog vs printf


The following code tries to compare the performance of syslog() with the printf() command. printf_vs_syslog.c (compressed) (136 downloads)
On our machine, it appears that syslog() is faster than printf().

To be as fair as possible, when the application was executing, we were monitoring the system logs as well, so that they will be printed on screen.
On CentOS 7, you can see the syslog in the file /var/log/messages.
The command we used was: sudo tail -f /var/log/messages

Results:

printf: Seconds elapsed 0.480000
syslog: Seconds elapsed 0.180000

Full source code for test:

printf_vs_syslog.c (compressed) (136 downloads)
#include <stdio.h>
#include <syslog.h>
// #include <stdlib.h> is needed for the resolution of EXIT_SUCCESS
#include <stdlib.h>
// #include <time.h> is needed for the clock() function and the macro CLOCKS_PER_SEC
#include <time.h>
// #include <unistd.h> and #include <sys/types.h> are needed for the functions uid_t getuid(void); and uid_t geteuid(void);
//getuid() returns the real user ID of the calling process.
//geteuid() returns the effective user ID of the calling process.
//These functions are always successful.
#include <unistd.h>
#include <sys/types.h>

#define RANGE (100000)

int main()
{
    {
        const clock_t start = clock();

        unsigned int i;
        for (i = 0; i < RANGE; i++){
            printf ("Program started by Real User %u (Effective User %u)\n", getuid(), geteuid());
        }
        printf("\n");

        const clock_t end = clock();
        const float seconds = (float) (end - start) / CLOCKS_PER_SEC;
        printf("printf: Seconds elapsed %f\n", seconds);
    }
    {
        const clock_t start = clock();

        setlogmask (LOG_UPTO (LOG_NOTICE));
        openlog ("bytefreaks", LOG_CONS | LOG_PID | LOG_NDELAY, LOG_LOCAL1);
        unsigned int i;
        for (i = 0; i < RANGE; i++){
            syslog (LOG_NOTICE, "Program started by Real User %u (Effective User %u)", getuid(), geteuid());
        }
        closelog ();

        const clock_t end = clock();
        const float seconds = (float) (end - start) / CLOCKS_PER_SEC;
        printf("syslog: Seconds elapsed %f\n", seconds);

    }
    return EXIT_SUCCESS;
}


printf_vs_syslog.c (compressed) (136 downloads)

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