[PATCH] Total io is the sum of READ and WRITE

[fio.git] / fio.h

diff --git a/fio.h b/fio.h
index e42d67bb137d721b92936e1249176c5ceabfee15..ddf66945d1b0e4cbbf84e6d5be7f830a73a93cfe 100644 (file)
--- a/fio.h
+++ b/fio.h
@@ -24,6 +24,9 @@ enum fio_ddir {
        DDIR_SYNC,
 };
 
+/*
+ * Use for maintaining statistics
+ */
 struct io_stat {
        unsigned long max_val;
        unsigned long min_val;
@@ -33,18 +36,27 @@ struct io_stat {
        double S;
 };
 
+/*
+ * A single data sample
+ */
 struct io_sample {
        unsigned long time;
        unsigned long val;
        enum fio_ddir ddir;
 };
 
+/*
+ * Dynamically growing data sample log
+ */
 struct io_log {
        unsigned long nr_samples;
        unsigned long max_samples;
        struct io_sample *log;
 };
 
+/*
+ * When logging io actions, this matches a single sent io_u
+ */
 struct io_piece {
        struct list_head list;
        struct fio_file *file;
@@ -71,10 +83,17 @@ struct io_u {
        struct timeval start_time;
        struct timeval issue_time;
 
+       /*
+        * Allocated/set buffer and length
+        */
        void *buf;
        unsigned int buflen;
        unsigned long long offset;
 
+       /*
+        * IO engine state, may be different from above when we get
+        * partial transfers / residual data counts
+        */
        void *xfer_buf;
        unsigned int xfer_buflen;
 
@@ -99,11 +118,14 @@ struct io_u {
 #define FIO_HDR_MAGIC  0xf00baaef
 
 enum {
-       VERIFY_NONE = 0,
-       VERIFY_MD5,
-       VERIFY_CRC32,
+       VERIFY_NONE = 0,                /* no verification */
+       VERIFY_MD5,                     /* md5 sum data blocks */
+       VERIFY_CRC32,                   /* crc32 sum data blocks */
 };
 
+/*
+ * A header structure associated with each checksummed data block
+ */
 struct verify_header {
        unsigned int fio_magic;
        unsigned int len;
@@ -136,20 +158,24 @@ enum fio_memtype {
  * The type of object we are working on
  */
 enum fio_filetype {
-       FIO_TYPE_FILE = 1,
-       FIO_TYPE_BD,
-       FIO_TYPE_CHAR,
+       FIO_TYPE_FILE = 1,              /* plain file */
+       FIO_TYPE_BD,                    /* block device */
+       FIO_TYPE_CHAR,                  /* character device */
 };
 
 enum fio_ioengine_flags {
-       FIO_SYNCIO      = 1 << 0,
-       FIO_CPUIO       = 1 << 1,
-       FIO_MMAPIO      = 1 << 2,
-       FIO_RAWIO       = 1 << 3,
-       FIO_NETIO       = 1 << 4,
-       FIO_NULLIO      = 1 << 5,
+       FIO_SYNCIO      = 1 << 0,       /* io engine has synchronous ->queue */
+       FIO_CPUIO       = 1 << 1,       /* cpu burner, doesn't do real io */
+       FIO_MMAPIO      = 1 << 2,       /* uses memory mapped io */
+       FIO_RAWIO       = 1 << 3,       /* some sort of direct/raw io */
+       FIO_NETIO       = 1 << 4,       /* networked io */
+       FIO_NULLIO      = 1 << 5,       /* no real data transfer (cpu/null) */
 };
 
+/*
+ * Each thread_data structure has a number of files associated with it,
+ * this structure holds state information for a single file.
+ */
 struct fio_file {
        /*
         * A file may not be a file descriptor, let the io engine decide
@@ -166,8 +192,12 @@ struct fio_file {
        unsigned long long last_pos;
        unsigned long long last_completed_pos;
 
+       /*
+        * block map for random io
+        */
        unsigned long *file_map;
        unsigned int num_maps;
+       unsigned int last_free_lookup;
 
        unsigned int unlink;
 };
@@ -407,6 +437,9 @@ static inline int should_fsync(struct thread_data *td)
        return 0;
 }
 
+/*
+ * Disk utils as read in /sys/block/<dev>/stat
+ */
 struct disk_util_stat {
        unsigned ios[2];
        unsigned merges[2];
@@ -416,6 +449,9 @@ struct disk_util_stat {
        unsigned time_in_queue;
 };
 
+/*
+ * Per-device disk util management
+ */
 struct disk_util {
        struct list_head list;
 
@@ -430,6 +466,9 @@ struct disk_util {
        struct timeval time;
 };
 
+/*
+ * Used for passing io_u completion data
+ */
 struct io_completion_data {
        int nr;                         /* input */