Linux/TMDXIDK5728: Linux RT general timing questions

Tool/software: Linux

Hello,

Is it possible to confirm the timing I am getting on Linux RT 03.03.00.04.

A thumb drive that looks like a USB 2 is connected to the IDK USB1 slot, which is a USB 3 connector.

Using clock_gettime(), which has nanosecond timing to find the length of time to write 1,000,000 ( 1 million) bytes to a file on the thumb drive. I have also been using the Linux 'time' command to confirm that my timing code was correct.

I am getting about 800 Mbits/second. I tried this on a desktop Ubuntu machine and getting 82 to 110 Mbits/second using the same thumb drive. And the read is still faster at up to 2700 Mbits/second. What I can find on the USB 2 specification says 480 Mbits/sec maximum. This appears to indicate a possible error in the clock information in the IDK AM5728 Linxu RT configuration.

I used the following code using the open, write, and close functions.

-----------------------------------------------------------

/*
        file_write_test.c

  An attempt to time the writing to a file on a USB flash drive
  that is mounted as a file directory partition.

  This creates a file.

*/

#include <stdio.h>
#include <stdint.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <time.h>

//################################################
// Globals
#define ARRLEN    1000000

//################################################
//
// FUNCTIONS

float timespecDiff(struct timespec *timeA_p, struct timespec *timeB_p)
{
  return (float) ((float) timeA_p->tv_sec + (float) (timeA_p->tv_nsec / 1000000000.0)) - ((float) timeB_p->tv_sec + (float) (timeB_p->tv_nsec / 1000000000.0));
}


//################################################
//
// MAIN

int main() {
    unsigned char txbytes[ARRLEN + 1];
    int i;
    struct timespec start, end; // Timing in seconds and nanoseconds
    float elapsed;

    // Puts some hex values in the array.
    for (i = 0; i < ARRLEN; i++)
    {
    txbytes[i] = (i % 10) + 48;
    //printf("\n\ttxbytes value: %c", txbytes[i]);
    }
    //printf("\n");
    //fflush(stdout);

    // Start timing
    clock_gettime(CLOCK_MONOTONIC, &start);

    int fd = open("/media/user01/UBUNTU 14_0/zfile001.txt", O_RDWR | O_CREAT);

    // Start timing
    write(fd, txbytes, ARRLEN);

    // Get amount of time to write to the newly opened and created file.

    close(fd);

    clock_gettime(CLOCK_MONOTONIC, &end);
    
    // Get read time difference
    elapsed = timespecDiff(&end, &start);
    fprintf(stderr, "\nElapsed time = %f seconds", elapsed);
    fprintf(stderr, "\nThe write rate is: %f bits/sec.\n\n", (float) (ARRLEN*8)/elapsed);

    return 0;
}