多线程复制 block 设备

Question

我试图找出在尝试并行比较和复制设备 block 与 pthreads 时我做错了什么。看起来我正在脱离同步并且比较阶段无法正常工作。任何帮助将不胜感激

#ifndef __dbg_h__
#define __dbg_h__

#define _LARGEFILE64_SOURCE
#define _GNU_SOURCE
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include <linux/fs.h>
#include <pthread.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdint.h>

#ifdef NDEBUG
#define debug(M, ...)
#else
#define debug(M, ...) fprintf(stderr, "DEBUG %s %s %s:%d: " M "\n", __DATE__,  __TIME__, __FILE__, __LINE__, ##__VA_ARGS__)
#endif

#define clean_errno() (errno == 0 ? "None" : strerror(errno))

#define log_err(M, ...) fprintf(stderr, "[ERROR] %s %s (%s:%d: errno: %s) " M "\n", __DATE__,  __TIME__, __FILE__, __LINE__, clean_errno(), ##__VA_ARGS__)

#define log_warn(M, ...) fprintf(stderr, "[WARN] %s %s (%s:%d: errno: %s) " M "\n", __DATE__,  __TIME__, __FILE__, __LINE__, clean_errno(), ##__VA_ARGS__)

#define log_info(M, ...) fprintf(stderr, "[INFO] %s %s (%s:%d) " M "\n", __DATE__,  __TIME__, __FILE__, __LINE__, ##__VA_ARGS__)

#endif

#define blksize 8192

void *compare_devices(void *arguments);

struct arg_struct {
    char device_name_a[1024];
    char device_name_b[1024];
    off_t start_offset;
    off_t end_offset;
    int thread_number;
    int sub_total;
};

int main(int argc, char **argv)
{
  int fd;
  long numblocks=0;
  int i;
  int err;
  long total_different_size=0;
  int number_of_threads=16;
  struct arg_struct compare_devices_args[number_of_threads];
  fd = open(argv[1], O_RDONLY);
  ioctl(fd, BLKGETSIZE, &numblocks);
  close(fd);
  log_info("Number of blocks: %lu, this makes %.3f GB\n",
         numblocks,
         (double)numblocks * 512.0 / (1024 * 1024 * 1024));
  //read_whole_device(argv[1]);
  long number_of_bytes_per_thread;
  number_of_bytes_per_thread=numblocks*512/(long)number_of_threads;
  pthread_t tid[number_of_threads];

  for (i=0; i<number_of_threads; i++) {
        strcpy(compare_devices_args[i].device_name_a, argv[1]);
        strcpy(compare_devices_args[i].device_name_b, argv[2]);
        compare_devices_args[i].start_offset=(long)(i*number_of_bytes_per_thread);
        compare_devices_args[i].end_offset=(long)((i+1)*number_of_bytes_per_thread-1);
        compare_devices_args[i].thread_number=i+1;
        err = pthread_create(&(tid[i]), NULL, &compare_devices,(void*)&compare_devices_args[i]);
        if (err != 0) {
            printf("\ncan't create thread :[%s]", strerror(err));
            return -1;
        }

  }
  for (i=0; i<number_of_threads; i++) {
        pthread_join(tid[i], NULL);
        total_different_size+=(long)compare_devices_args[i].sub_total;
  }
  printf ("Total of Different size between devices - %ld\n",total_different_size);
};


int read_n_bytes_from(int fd, off_t pos, char *buf, int n)
{
       if (lseek(fd, pos, SEEK_SET) >= 0)
           return read(fd, buf, n);
       else
           return -1;
}

void read_whole_device(char* device_name)
{
        int fd;
        char buf[1024*1024];
        size_t size;
        int counter=0;
        log_info("reading device %s\n",device_name);
        fd = open(device_name, O_RDONLY|O_NONBLOCK);
        //ssize_t size = read(fd, &buf, 1024);
        lseek(fd, 0, SEEK_SET);
        while ( (size=read(fd, buf, 1024*1024)) > 0 ) {
                printf("Read buffer %d - %d\n", size, counter);
                counter++;
        }
        close(fd);
}

void write_block_to_device(int fd,off_t pos,char* buf, int n)
{
        if (lseek(fd, pos, SEEK_SET) >= 0) {
                //write
        }
}

void compare_buffer(char* buf_first,char* buf_second,int length, int blk_size, int* result)
{
        int i;
        char buf_cpy[blk_size];
        for (i=0; i<=(length/blk_size);i++)
        {
                if ( memcmp(buf_first+(blk_size*i), buf_second+(blk_size*i),  blk_size) != 0) {
                        //printf ("Block %d is different\n",i);
                        result[i]=1;
                }
                else {
                        result[i]=0;
                }
        }
}

void *compare_devices(void *arguments)
{
        struct arg_struct *args = arguments;
        int fd_first,fd_second;
        char buf_first[1024*1024];
        char buf_second[1024*104];
        int size_first,size_second;
        int counter=0;
        int result[128];
        int memcmp_result;
        int i;
        off_t pos,pos_first,pos_second;
        int total_number_of_different_blocks,difference_in_mb;
        long number_of_mb_to_scan=0;
        total_number_of_different_blocks=0;
        log_info("Thread %d - compare devices %s,%s - start %ld end %ld\n",args->thread_number,args->device_name_a,args->device_name_b,args->start_offset,args->end_offset);
        fd_first = open(args->device_name_a, O_RDONLY);
        fd_second = open(args->device_name_b, O_RDONLY);
        log_info("Thread %d - %d %d\n",args->thread_number,fd_first,fd_second);
        log_info("Thread %d - before lseek - %ld %ld\n",args->thread_number,lseek(fd_first, 0, SEEK_CUR),lseek(fd_second, 0, SEEK_CUR));
        lseek(fd_first, (off_t)args->start_offset, SEEK_SET);
        lseek(fd_second, (off_t)args->start_offset, SEEK_SET);
        log_info("Thread %d - after lseek - %ld %ld\n",args->thread_number,lseek(fd_first, 0, SEEK_CUR),lseek(fd_second, 0, SEEK_CUR));
        log_info("Thread %d - start %ld , %ld\n",args->thread_number,lseek(fd_first, 0, SEEK_CUR),lseek(fd_second, 0, SEEK_CUR));
        number_of_mb_to_scan=(args->end_offset-args->start_offset)/1024/1024;
        log_info("Thread %d - Number of MB to scan %ld - start offset %ld\n",args->thread_number,number_of_mb_to_scan,lseek(fd_second, 0, SEEK_CUR));
        memset(buf_first, 0, sizeof(buf_first));
        memset(buf_second, 0, sizeof(buf_second));
        while ( (size_first=read(fd_first, buf_first, 1024*1024)) > 0 ) {
                size_second=read(fd_second,buf_second, 1024*1024);
                pos_first=lseek(fd_first, 0, SEEK_CUR);
                pos_second=lseek(fd_second, 0, SEEK_CUR);
                log_info("Thread %d - fd (%d,%d) pos_first %lld, pos_second %lld (%d - %d) - read %d,%d\n",args->thread_number,fd_first,fd_second,(unsigned long long)pos_first-1024*1024,(unsigned long long)pos_second-1024*1024,sizeof(off_t),sizeof(pos),size_first,size_second);
                //log_info("Thread %s - Hash Buf A - %ld Hash Buf B - %ld",args->thread_number,adler32(buf_first,size_first),adler32(buf_second,size_second));
                if ( (memcmp_result=memcmp(buf_first, buf_second, sizeof(buf_second))) != 0 ) {
                        log_info("Thread %d - Found 1MB chunck which is different at pos %lld - %d (%d)\n",args->thread_number,(unsigned long long)pos_first-1024*1024, memcmp_result,sizeof(buf_first));
                        compare_buffer(buf_first,buf_second,1024*1024,blksize,result);
                        for (i=0; i<=128; i++) {
                                if ( result[i] == 1 ) {
                                        //printf ("%d,",result[i]);
                                        total_number_of_different_blocks++;
                                }
                        }
                }
                if ( pos_first > args->end_offset ) {
                        break;
                }
                memset(buf_first, 0, sizeof(buf_first));
                memset(buf_second, 0, sizeof(buf_second));
                counter++;
        }
        log_info("Thread %d - Number of MB to scan %ld - end offset %ld\n",args->thread_number,number_of_mb_to_scan,lseek(fd_first, 0, SEEK_CUR));
        log_info("Thread %d - Completed - Scanning %d of 1MB chuncks\n",args->thread_number,counter);
        log_info("Thread %d - Diffence of size between %s to %s starting at %ld and ending at %ld- %d different blocks of 8k - %dMB\n",args->thread_number,args->device_name_a,args->device_name_b,args->start_offset,args->end_offset,total_number_of_different_blocks,total_number_of_different_blocks*8192/1024/1024);
        args->sub_total=total_number_of_different_blocks/8/1024;
        close(fd_first);
        close(fd_second);
        pthread_exit(arguments);
}

更新版本:

#ifndef __dbg_h__
#define __dbg_h__

#define _LARGEFILE64_SOURCE
#define _GNU_SOURCE
#define _FILE_OFFSET_BITS 64
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include <linux/fs.h>
#include <pthread.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdint.h>
#include <getopt.h>
#include <openssl/sha.h>
#include <sched.h>

#ifdef NDEBUG
#define debug(M, ...)
#else
#define debug(M, ...) fprintf(stderr, "DEBUG %s %s %s:%d: " M "\n", __DATE__,  __TIME__, __FILE__, __LINE__, ##__VA_ARGS__)
#endif

#define clean_errno() (errno == 0 ? "None" : strerror(errno))

#define log_err(M, ...) fprintf(stderr, "[ERROR] %s %s (%s:%d: errno: %s) " M "\n", __DATE__,  __TIME__, __FILE__, __LINE__, clean_er
rno(), ##__VA_ARGS__)

#define log_warn(M, ...) fprintf(stderr, "[WARN] %s %s (%s:%d: errno: %s) " M "\n", __DATE__,  __TIME__, __FILE__, __LINE__, clean_er
rno(), ##__VA_ARGS__)

#define log_info(M, ...) fprintf(stderr, "[INFO] %s %s (%s:%d) " M "\n", __DATE__,  __TIME__, __FILE__, __LINE__, ##__VA_ARGS__)

#endif

#ifndef _TRY_THROW_CATCH_H_
#define _TRY_THROW_CATCH_H_

#include <setjmp.h>

#define TRY do { jmp_buf ex_buf__; switch( setjmp(ex_buf__) ) { case 0: while(1) {
#define CATCH(x) break; case x:
#define FINALLY break; } default: {
#define ETRY break; } } }while(0)
#define THROW(x) longjmp(ex_buf__, x)

#endif /*!_TRY_THROW_CATCH_H_*/

unsigned long long chunck_size=1024*1024;
int blksize=16384;
int cb=0;

void *compare_devices(void *arguments);

struct arg_struct {
    char device_name_a[1024];
    char device_name_b[1024];
    off64_t start_offset;
    off64_t end_offset;
    int thread_number;
    int sub_total;
};

int main(int argc, char **argv)
{
  int fd,s_is_set=0,d_is_set=0,copy_blocks=0,num_cpus;
  int opt;
  char *source_device,*dest_device,*blksize_string,*number_of_threads_string;
  long numblocks_src=0,numblocks_dst=0;
  int i;
  int err,policy;
  long total_different_size=0;
  int number_of_threads=16;
  int newprio, set_thread_priority=0;
  pthread_attr_t tattr;
  struct sched_param param;
  while ((opt = getopt(argc, argv, "s:d:b:p:t:c")) != -1) {
    switch (opt) {
    case 's':
        source_device = optarg;
        log_info("source device is %s\n",source_device);
        s_is_set=1;
        if( access( source_device, F_OK ) != -1 ) {
            log_info("source device is accessible\n");
        }
        else {
            log_err("cannot access source device\n");
            return -1;
        }
        break;
    case 'd':
        dest_device = optarg;
        log_info("dest device is %s\n",dest_device);
        d_is_set=1;
        if( access( dest_device, F_OK ) != -1 ) {
            log_info("dest device is accessible\n");
        }
        else {
            log_err("cannot access dest device\n");
            return -1;
        }
        break;
    case 'b':
        blksize = atoi(optarg);
        if (blksize%4096 != 0) {
            log_err("Block Size is not multiple of 4k\n");
            return -1;
        }
        else
            log_info("block size is %d\n",blksize);
        break;
    case 't':
        number_of_threads = atoi(optarg);
        num_cpus = sysconf( _SC_NPROCESSORS_ONLN );
        if ( number_of_threads%2 != 0 ) {
            log_err("Number of threads are not multiple of 2\n");
            return -1;
        }
        else
            log_info("number of threads is %d - number of cores %d\n",number_of_threads,num_cpus);
            if ( number_of_threads > num_cpus ) {
                number_of_threads=num_cpus;
           }
        break;
    case 'c':
        copy_blocks=1;
        cb=1;
        break;
    case 'p':
        if ( optarg != NULL ) {
            newprio=atoi(optarg);
            set_thread_priority=1;
        }
        break;
    case ':':
        log_info("%s: option '-%c' requires an argument\n",argv[0], optopt);
        break;
    case '?':
    default:
        log_info("%s: option '-%c' is invalid: ignored\n",argv[0], optopt);
        break;
    }
  }
  if ( s_is_set != 1 || d_is_set !=1 ) {
      log_err("Source device and Destination device must be specified\n");
      return -1;
  }
  struct arg_struct compare_devices_args[number_of_threads];
  fd = open(source_device, O_RDONLY);
  ioctl(fd, BLKGETSIZE, &numblocks_src);
  close(fd);
  log_info("Number of blocks in source device: %lu, this makes %.3f GB\n", numblocks_src, (double)numblocks_src * 512.0 / (1024 * 102
4 * 1024));
  fd = open(dest_device, O_RDONLY);
  ioctl(fd, BLKGETSIZE, &numblocks_dst);
  close(fd);
  log_info("Number of blocks in destination is device: %lu, this makes %.3f GB\n", numblocks_dst, (double)numblocks_dst * 512.0 / (10
24 * 1024 * 1024));
  if ( numblocks_src > numblocks_dst ) {
      log_info("Number of blocks in source device is larger then number of blocks in destination device");
      return -1;
  }
  long number_of_bytes_per_thread;
  number_of_bytes_per_thread=numblocks_src*512/(long)number_of_threads;
  pthread_t tid[number_of_threads];
  for (i=0; i<number_of_threads; i++) {
        strcpy(compare_devices_args[i].device_name_a, source_device);
        strcpy(compare_devices_args[i].device_name_b, dest_device);
        compare_devices_args[i].start_offset=(long)(i*number_of_bytes_per_thread);
        compare_devices_args[i].end_offset=(long)((i+1)*number_of_bytes_per_thread-1);
        compare_devices_args[i].thread_number=i+1;
        if ( set_thread_priority == 1 ) {
            err = pthread_attr_init (&tattr);
            policy = SCHED_RR;
            err = pthread_attr_setschedpolicy(&tattr, policy);
            if (err != 0) {
                log_err("\nThread %d - Unable to set scheduler policy attributes :[%s]", i+1, strerror(err));
            }
            err = pthread_attr_getschedparam (&tattr, &param);
            if (err != 0) {
                log_err("\nThread %d - Unable to get scheduler priority attributes :[%s]", i+1, strerror(err));
            }
            log_info("\nThread %d - Old thread priority is %d",i+1,param.sched_priority);
            param.sched_priority = newprio;
            log_info("\nThread %d - Setting pthread priority to %d",i+1,newprio);
            err = pthread_attr_setschedparam (&tattr, &param);
            if (err != 0) {
                log_err("\nThread %d - Unable to set scheduler attributes :[%s]", i+1, strerror(err));
            }
            err = pthread_create(&(tid[i]), &tattr, &compare_devices,(void*)&compare_devices_args[i]);
        }
        else
        {
            err = pthread_create(&(tid[i]), NULL, &compare_devices,(void*)&compare_devices_args[i]);
        }
        if (err != 0) {
            log_err("\nThread %d - can't create thread :[%s]", i+1, strerror(err));
            return -1;
        }

  }
  for (i=0; i<number_of_threads; i++) {
        pthread_join(tid[i], NULL);
        total_different_size+=(long)compare_devices_args[i].sub_total;
  }
  log_info ("Total of Different size between devices - %ld\n",total_different_size);
};


void compare_buffer(char* buf_first,char* buf_second,int length, int blk_size, int* result)
{
        int i;
        char buf_cpy[blk_size];
        for (i=0; i<=(length/blk_size);i++)
        {
                if ( memcmp(buf_first+(blk_size*i), buf_second+(blk_size*i),  blk_size) != 0) {
                        result[i]=1;
                }
                else {
                        result[i]=0;
                }
        }
}

void *compare_devices(void *arguments)
{
        struct arg_struct *args = arguments;
        int fd_first,fd_second;
        char buf_first[chunck_size];
        char buf_second[chunck_size];
        int size_first,size_second;
        unsigned int counter=0;
        int result[chunck_size/blksize];
        int memcmp_result;
        unsigned long long i;
        off64_t pos,pos_first,pos_second;
        unsigned long long total_number_of_different_blocks,difference_in_mb;
        long number_of_mb_to_scan=0;
        total_number_of_different_blocks=0;
        log_info("Thread %d - compare devices %s,%s - start %llu end %llu\n",args->thread_number,args->device_name_a,args->device_nam
e_b,args->start_offset,args->end_offset);
        fd_first = open(args->device_name_a, O_RDONLY);
        if ( cb == 0 ) {
            fd_second = open(args->device_name_b, O_RDONLY);
        }
        else
            fd_second = open(args->device_name_b, O_RDWR);
        lseek64(fd_first, (off64_t)args->start_offset, SEEK_SET);
        lseek64(fd_second, (off64_t)args->start_offset, SEEK_SET);
        number_of_mb_to_scan=(args->end_offset-args->start_offset)/chunck_size;
        debug("Thread %d - Number of MB to scan %ld - start offset %ld\n",args->thread_number,number_of_mb_to_scan,lseek64(fd_second,
 0, SEEK_CUR));
        memset(buf_first, 0, sizeof(buf_first));
        memset(buf_second, 0, sizeof(buf_second));
        while ( (size_first=read(fd_first, buf_first, chunck_size)) > 0 && counter <= number_of_mb_to_scan ) {
                size_second=read(fd_second,buf_second, chunck_size);
                pos_first=lseek64(fd_first, 0, SEEK_CUR);
                pos_second=lseek64(fd_second, 0, SEEK_CUR);
                if ( (memcmp_result=memcmp(buf_first, buf_second, sizeof(buf_second))) != 0 ) {
                        debug("Thread %d - Found 1MB chunck which is different at pos %llu - %d (%d)\n",args->thread_number,(unsigned
 long long)pos_first-chunck_size, memcmp_result,sizeof(buf_first));
                        compare_buffer(buf_first,buf_second,chunck_size,blksize,result);
                        for (i=0; i<=chunck_size/blksize; i++) {
                                if ( result[i] == 1 ) {
                                        if ( cb == 1 ) {
                                            debug("Thread %d - chunck %d - copying block %d - location of block in device file %llu",
 args->thread_number, counter+1, i, args->start_offset+(unsigned long long)(chunck_size*counter)+(unsigned long long)(i*blksize));
                                            lseek64(fd_first,args->start_offset+(off64_t)(chunck_size*counter)+(off64_t)(i*blksize),S
EEK_SET);
                                            lseek64(fd_second,args->start_offset+(off64_t)(chunck_size*counter)+(off64_t)(i*blksize),
SEEK_SET);
                                            size_first=read(fd_first, buf_first, blksize);
                                            size_second=write(fd_second,buf_first,size_first);
                                            if ( size_second != blksize ) {
                                                log_err("Thread %d - Houston we have a problem in copying block number %llu",args->th
read_number, (unsigned long long)args->start_offset+(unsigned long long)(chunck_size*counter)+(unsigned long long)(i*blksize));
                                            }
                                        }
                                        total_number_of_different_blocks++;
                                }
                        }
                }
                if ( cb == 1) {
                        lseek64(fd_second,(off64_t)args->start_offset+(off64_t)(chunck_size*(counter+1)),SEEK_SET);
                        lseek64(fd_first,(off64_t)args->start_offset+(off64_t)(chunck_size*(counter+1)),SEEK_SET);
                }
                if ( pos_first > args->end_offset ) {
                        break;
                }
                memset(buf_first, 0, sizeof(buf_first));
                memset(buf_second, 0, sizeof(buf_second));
                debug("Thread %d - chunck %d out of %d done - %llu %llu", args->thread_number, counter+1, number_of_mb_to_scan,pos_fi
rst,args->end_offset);
                counter++;
        }
        log_info("Thread %d - Number of MB to scan %ld - end offset %llu\n",args->thread_number,number_of_mb_to_scan,lseek64(fd_first
, 0, SEEK_CUR));
        log_info("Thread %d - Completed - Scanning %d of 1MB chuncks\n",args->thread_number,counter);
        log_info("Thread %d - Difference of size between %s to %s starting at %llu and ending at %llu- %d different blocks of %d - %d
MB\n",args->thread_number,args->device_name_a,args->device_name_b,args->start_offset,args->end_offset,total_number_of_different_block
s,blksize,total_number_of_different_blocks*blksize/chunck_size);
        args->sub_total=total_number_of_different_blocks*blksize/1024;
        close(fd_first);
        close(fd_second);
        pthread_exit(arguments);
}

Answer 1

#ifndef __dbg_h__
#define __dbg_h__

#define _LARGEFILE64_SOURCE
#define _GNU_SOURCE
#define _FILE_OFFSET_BITS 64
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include <linux/fs.h>
#include <pthread.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdint.h>
#include <getopt.h>
#include <openssl/sha.h>
#include <sched.h>

#ifdef NDEBUG
#define debug(M, ...)
#else
#define debug(M, ...) fprintf(stderr, "DEBUG %s %s %s:%d: " M "\n", __DATE__,  __TIME__, __FILE__, __LINE__, ##__VA_ARGS__)
#endif

#define clean_errno() (errno == 0 ? "None" : strerror(errno))

#define log_err(M, ...) fprintf(stderr, "[ERROR] %s %s (%s:%d: errno: %s) " M "\n", __DATE__,  __TIME__, __FILE__, __LINE__, clean_er
rno(), ##__VA_ARGS__)

#define log_warn(M, ...) fprintf(stderr, "[WARN] %s %s (%s:%d: errno: %s) " M "\n", __DATE__,  __TIME__, __FILE__, __LINE__, clean_er
rno(), ##__VA_ARGS__)

#define log_info(M, ...) fprintf(stderr, "[INFO] %s %s (%s:%d) " M "\n", __DATE__,  __TIME__, __FILE__, __LINE__, ##__VA_ARGS__)

#endif

#ifndef _TRY_THROW_CATCH_H_
#define _TRY_THROW_CATCH_H_

#include <setjmp.h>

#define TRY do { jmp_buf ex_buf__; switch( setjmp(ex_buf__) ) { case 0: while(1) {
#define CATCH(x) break; case x:
#define FINALLY break; } default: {
#define ETRY break; } } }while(0)
#define THROW(x) longjmp(ex_buf__, x)

#endif /*!_TRY_THROW_CATCH_H_*/

unsigned long long chunck_size=1024*1024;
int blksize=16384;
int cb=0;

void *compare_devices(void *arguments);

struct arg_struct {
    char device_name_a[1024];
    char device_name_b[1024];
    off64_t start_offset;
    off64_t end_offset;
    int thread_number;
    int sub_total;
};

int main(int argc, char **argv)
{
  int fd,s_is_set=0,d_is_set=0,copy_blocks=0,num_cpus;
  int opt;
  char *source_device,*dest_device,*blksize_string,*number_of_threads_string;
  long numblocks_src=0,numblocks_dst=0;
  int i;
  int err,policy;
  long total_different_size=0;
  int number_of_threads=16;
  int newprio, set_thread_priority=0;
  pthread_attr_t tattr;
  struct sched_param param;
  while ((opt = getopt(argc, argv, "s:d:b:p:t:c")) != -1) {
    switch (opt) {
    case 's':
        source_device = optarg;
        log_info("source device is %s\n",source_device);
        s_is_set=1;
        if( access( source_device, F_OK ) != -1 ) {
            log_info("source device is accessible\n");
        }
        else {
            log_err("cannot access source device\n");
            return -1;
        }
        break;
    case 'd':
        dest_device = optarg;
        log_info("dest device is %s\n",dest_device);
        d_is_set=1;
        if( access( dest_device, F_OK ) != -1 ) {
            log_info("dest device is accessible\n");
        }
        else {
            log_err("cannot access dest device\n");
            return -1;
        }
        break;
    case 'b':
        blksize = atoi(optarg);
        if (blksize%4096 != 0) {
            log_err("Block Size is not multiple of 4k\n");
            return -1;
        }
        else
            log_info("block size is %d\n",blksize);
        break;
    case 't':
        number_of_threads = atoi(optarg);
        num_cpus = sysconf( _SC_NPROCESSORS_ONLN );
        if ( number_of_threads%2 != 0 ) {
            log_err("Number of threads are not multiple of 2\n");
            return -1;
        }
        else
            log_info("number of threads is %d - number of cores %d\n",number_of_threads,num_cpus);
            if ( number_of_threads > num_cpus ) {
                number_of_threads=num_cpus;
           }
        break;
    case 'c':
        copy_blocks=1;
        cb=1;
        break;
    case 'p':
        if ( optarg != NULL ) {
            newprio=atoi(optarg);
            set_thread_priority=1;
        }
        break;
    case ':':
        log_info("%s: option '-%c' requires an argument\n",argv[0], optopt);
        break;
    case '?':
    default:
        log_info("%s: option '-%c' is invalid: ignored\n",argv[0], optopt);
        break;
    }
  }
  if ( s_is_set != 1 || d_is_set !=1 ) {
      log_err("Source device and Destination device must be specified\n");
      return -1;
  }
  struct arg_struct compare_devices_args[number_of_threads];
  fd = open(source_device, O_RDONLY);
  ioctl(fd, BLKGETSIZE, &numblocks_src);
  close(fd);
  log_info("Number of blocks in source device: %lu, this makes %.3f GB\n", numblocks_src, (double)numblocks_src * 512.0 / (1024 * 102
4 * 1024));
  fd = open(dest_device, O_RDONLY);
  ioctl(fd, BLKGETSIZE, &numblocks_dst);
  close(fd);
  log_info("Number of blocks in destination is device: %lu, this makes %.3f GB\n", numblocks_dst, (double)numblocks_dst * 512.0 / (10
24 * 1024 * 1024));
  if ( numblocks_src > numblocks_dst ) {
      log_info("Number of blocks in source device is larger then number of blocks in destination device");
      return -1;
  }
  long number_of_bytes_per_thread;
  number_of_bytes_per_thread=numblocks_src*512/(long)number_of_threads;
  pthread_t tid[number_of_threads];
  for (i=0; i<number_of_threads; i++) {
        strcpy(compare_devices_args[i].device_name_a, source_device);
        strcpy(compare_devices_args[i].device_name_b, dest_device);
        compare_devices_args[i].start_offset=(long)(i*number_of_bytes_per_thread);
        compare_devices_args[i].end_offset=(long)((i+1)*number_of_bytes_per_thread-1);
        compare_devices_args[i].thread_number=i+1;
        if ( set_thread_priority == 1 ) {
            err = pthread_attr_init (&tattr);
            policy = SCHED_RR;
            err = pthread_attr_setschedpolicy(&tattr, policy);
            if (err != 0) {
                log_err("\nThread %d - Unable to set scheduler policy attributes :[%s]", i+1, strerror(err));
            }
            err = pthread_attr_getschedparam (&tattr, &param);
            if (err != 0) {
                log_err("\nThread %d - Unable to get scheduler priority attributes :[%s]", i+1, strerror(err));
            }
            log_info("\nThread %d - Old thread priority is %d",i+1,param.sched_priority);
            param.sched_priority = newprio;
            log_info("\nThread %d - Setting pthread priority to %d",i+1,newprio);
            err = pthread_attr_setschedparam (&tattr, &param);
            if (err != 0) {
                log_err("\nThread %d - Unable to set scheduler attributes :[%s]", i+1, strerror(err));
            }
            err = pthread_create(&(tid[i]), &tattr, &compare_devices,(void*)&compare_devices_args[i]);
        }
        else
        {
            err = pthread_create(&(tid[i]), NULL, &compare_devices,(void*)&compare_devices_args[i]);
        }
        if (err != 0) {
            log_err("\nThread %d - can't create thread :[%s]", i+1, strerror(err));
            return -1;
        }

  }
  for (i=0; i<number_of_threads; i++) {
        pthread_join(tid[i], NULL);
        total_different_size+=(long)compare_devices_args[i].sub_total;
  }
  log_info ("Total of Different size between devices - %ld\n",total_different_size);
};


void compare_buffer(char* buf_first,char* buf_second,int length, int blk_size, int* result)
{
        int i;
        char buf_cpy[blk_size];
        for (i=0; i<=(length/blk_size);i++)
        {
                if ( memcmp(buf_first+(blk_size*i), buf_second+(blk_size*i),  blk_size) != 0) {
                        result[i]=1;
                }
                else {
                        result[i]=0;
                }
        }
}

void *compare_devices(void *arguments)
{
        struct arg_struct *args = arguments;
        int fd_first,fd_second;
        char buf_first[chunck_size];
        char buf_second[chunck_size];
        int size_first,size_second;
        unsigned int counter=0;
        int result[chunck_size/blksize];
        int memcmp_result;
        unsigned long long i;
        off64_t pos,pos_first,pos_second;
        unsigned long long total_number_of_different_blocks,difference_in_mb;
        long number_of_mb_to_scan=0;
        total_number_of_different_blocks=0;
        log_info("Thread %d - compare devices %s,%s - start %llu end %llu\n",args->thread_number,args->device_name_a,args->device_nam
e_b,args->start_offset,args->end_offset);
        fd_first = open(args->device_name_a, O_RDONLY);
        if ( cb == 0 ) {
            fd_second = open(args->device_name_b, O_RDONLY);
        }
        else
            fd_second = open(args->device_name_b, O_RDWR);
        lseek64(fd_first, (off64_t)args->start_offset, SEEK_SET);
        lseek64(fd_second, (off64_t)args->start_offset, SEEK_SET);
        number_of_mb_to_scan=(args->end_offset-args->start_offset)/chunck_size;
        debug("Thread %d - Number of MB to scan %ld - start offset %ld\n",args->thread_number,number_of_mb_to_scan,lseek64(fd_second,
 0, SEEK_CUR));
        memset(buf_first, 0, sizeof(buf_first));
        memset(buf_second, 0, sizeof(buf_second));
        while ( (size_first=read(fd_first, buf_first, chunck_size)) > 0 && counter <= number_of_mb_to_scan ) {
                size_second=read(fd_second,buf_second, chunck_size);
                pos_first=lseek64(fd_first, 0, SEEK_CUR);
                pos_second=lseek64(fd_second, 0, SEEK_CUR);
                if ( (memcmp_result=memcmp(buf_first, buf_second, sizeof(buf_second))) != 0 ) {
                        debug("Thread %d - Found 1MB chunck which is different at pos %llu - %d (%d)\n",args->thread_number,(unsigned
 long long)pos_first-chunck_size, memcmp_result,sizeof(buf_first));
                        compare_buffer(buf_first,buf_second,chunck_size,blksize,result);
                        for (i=0; i<=chunck_size/blksize; i++) {
                                if ( result[i] == 1 ) {
                                        if ( cb == 1 ) {
                                            debug("Thread %d - chunck %d - copying block %d - location of block in device file %llu",
 args->thread_number, counter+1, i, args->start_offset+(unsigned long long)(chunck_size*counter)+(unsigned long long)(i*blksize));
                                            lseek64(fd_first,args->start_offset+(off64_t)(chunck_size*counter)+(off64_t)(i*blksize),S
EEK_SET);
                                            lseek64(fd_second,args->start_offset+(off64_t)(chunck_size*counter)+(off64_t)(i*blksize),
SEEK_SET);
                                            size_first=read(fd_first, buf_first, blksize);
                                            size_second=write(fd_second,buf_first,size_first);
                                            if ( size_second != blksize ) {
                                                log_err("Thread %d - Houston we have a problem in copying block number %llu",args->th
read_number, (unsigned long long)args->start_offset+(unsigned long long)(chunck_size*counter)+(unsigned long long)(i*blksize));
                                            }
                                        }
                                        total_number_of_different_blocks++;
                                }
                        }
                }
                if ( cb == 1) {
                        lseek64(fd_second,(off64_t)args->start_offset+(off64_t)(chunck_size*(counter+1)),SEEK_SET);
                        lseek64(fd_first,(off64_t)args->start_offset+(off64_t)(chunck_size*(counter+1)),SEEK_SET);
                }
                if ( pos_first > args->end_offset ) {
                        break;
                }
                memset(buf_first, 0, sizeof(buf_first));
                memset(buf_second, 0, sizeof(buf_second));
                debug("Thread %d - chunck %d out of %d done - %llu %llu", args->thread_number, counter+1, number_of_mb_to_scan,pos_fi
rst,args->end_offset);
                counter++;
        }
        log_info("Thread %d - Number of MB to scan %ld - end offset %llu\n",args->thread_number,number_of_mb_to_scan,lseek64(fd_first
, 0, SEEK_CUR));
        log_info("Thread %d - Completed - Scanning %d of 1MB chuncks\n",args->thread_number,counter);
        log_info("Thread %d - Difference of size between %s to %s starting at %llu and ending at %llu- %d different blocks of %d - %d
MB\n",args->thread_number,args->device_name_a,args->device_name_b,args->start_offset,args->end_offset,total_number_of_different_block
s,blksize,total_number_of_different_blocks*blksize/chunck_size);
        args->sub_total=total_number_of_different_blocks*blksize/1024;
        close(fd_first);
        close(fd_second);
        pthread_exit(arguments);
}