diff options
| -rw-r--r-- | disk_perf.c | 94 |
1 files changed, 47 insertions, 47 deletions
diff --git a/disk_perf.c b/disk_perf.c index 81c4095..9efd97a 100644 --- a/disk_perf.c +++ b/disk_perf.c @@ -8,61 +8,61 @@ #include <sys/time.h> static uint64_t gettimestamp() { - struct timeval tv; - gettimeofday(&tv, NULL); - return tv.tv_sec * 1000000ULL + tv.tv_usec; + struct timeval tv; + gettimeofday(&tv, NULL); + return tv.tv_sec * 1000000ULL + tv.tv_usec; } static void writeall(int fd, const void *buf, size_t count) { - size_t cursor = 0; - while (cursor < count) { - ssize_t written = write(fd, buf + cursor, count - cursor); - if (written < 0) { - perror("write"); - exit(1); - } - assert(written > 0); - cursor += written; - } + size_t cursor = 0; + while (cursor < count) { + ssize_t written = write(fd, buf + cursor, count - cursor); + if (written < 0) { + perror("write"); + exit(1); + } + assert(written > 0); + cursor += written; + } } int main(int argc, char **argv) { - if (argc != 2) { - fprintf(stderr, "Usage: %s <temp file to use>\n", argv[0]); - fprintf(stderr, - "This will write some data to a file as many times per second as\n" - "possible, calling fsync() after each write to make sure it is\n" - "persisted. This gives an upper bound on the number of ACID transactions\n" - "a single-threaded database can achieve on a disk.\n" - "The amount of data in one write is currently 18 bytes.\n" - ); - return 1; - } + if (argc != 2) { + fprintf(stderr, "Usage: %s <temp file to use>\n", argv[0]); + fprintf(stderr, + "This will write some data to a file as many times per second as\n" + "possible, calling fsync() after each write to make sure it is\n" + "persisted. This gives an upper bound on the number of ACID transactions\n" + "a single-threaded database can achieve on a disk.\n" + "The amount of data in one write is currently 18 bytes.\n" + ); + return 1; + } - int fd = open(argv[1], O_WRONLY | O_CREAT, 0644); - if (fd < 0) { - perror("open"); - return 1; - } + int fd = open(argv[1], O_WRONLY | O_CREAT, 0644); + if (fd < 0) { + perror("open"); + return 1; + } - uint64_t start_stamp = gettimestamp(); - size_t num_writes = 0; - for (size_t i = 0; ; i++) { - const char *str = "abcdefgh=01234567\n"; - writeall(fd, str, strlen(str)); - fsync(fd); - num_writes++; + uint64_t start_stamp = gettimestamp(); + size_t num_writes = 0; + for (size_t i = 0; ; i++) { + const char *str = "abcdefgh=01234567\n"; + writeall(fd, str, strlen(str)); + fsync(fd); + num_writes++; - if (i % 100 == 0) { - uint64_t now = gettimestamp(); - double secs = (double)(now - start_stamp) / 1000000; - if (secs >= 4.0) { - printf("Speed: %zu writes in %lf seconds = %lf w/s\n", - num_writes, secs, num_writes / secs); + if (i % 100 == 0) { + uint64_t now = gettimestamp(); + double secs = (double)(now - start_stamp) / 1000000; + if (secs >= 4.0) { + printf("Speed: %zu writes in %lf seconds = %lf w/s\n", + num_writes, secs, num_writes / secs); - start_stamp = now; - num_writes = 0; - } - } - } + start_stamp = now; + num_writes = 0; + } + } + } } |