blktrace fixup + documentation

[fio.git] / blktrace.c

diff --git a/blktrace.c b/blktrace.c
index 178a2a35eb57b4ac7d47b8a1acd6dd81e4154f75..1669fe556bc3324d2b40567e0afdab0f0e359667 100644 (file)
--- a/blktrace.c
+++ b/blktrace.c
@@ -3,10 +3,14 @@
  */
 #include <stdio.h>
 #include <stdlib.h>
+
 #include "list.h"
 #include "fio.h"
 #include "blktrace_api.h"
 
+/*
+ * Just discard the pdu by seeking past it.
+ */
 static int discard_pdu(int fd, struct blk_io_trace *t)
 {
        if (t->pdu_len == 0)
@@ -18,6 +22,10 @@ static int discard_pdu(int fd, struct blk_io_trace *t)
        return 0;
 }
 
+/*
+ * Check if this is a blktrace binary data file. We read a single trace
+ * into memory and check for the magic signature.
+ */
 int is_blktrace(const char *filename)
 {
        struct blk_io_trace t;
@@ -46,13 +54,65 @@ int is_blktrace(const char *filename)
        return 0;
 }
 
-static void handle_trace(struct thread_data *td, struct blk_io_trace *t)
+/*
+ * Store blk_io_trace data in an ipo for later retrieval.
+ */
+static void store_ipo(struct thread_data *td, unsigned long long offset,
+                     unsigned int bytes, int rw, unsigned long long ttime)
 {
+       struct io_piece *ipo = malloc(sizeof(*ipo));
+
+       memset(ipo, 0, sizeof(*ipo));
+       INIT_LIST_HEAD(&ipo->list);
+       /*
+        * the 512 is wrong here, it should be the hardware sector size...
+        */
+       ipo->offset = offset * 512;
+       ipo->len = bytes;
+       ipo->delay = ttime / 1000;
+       if (rw)
+               ipo->ddir = DDIR_WRITE;
+       else
+               ipo->ddir = DDIR_READ;
+
+       list_add_tail(&ipo->list, &td->io_log_list);
 }
 
+/*
+ * We only care for queue traces, most of the others are side effects
+ * due to internal workings of the block layer.
+ */
+static void handle_trace(struct thread_data *td, struct blk_io_trace *t,
+                        unsigned long long ttime, unsigned long *ios)
+{
+       int rw;
+
+       if ((t->action & 0xffff) != __BLK_TA_QUEUE)
+               return;
+       if (t->action & BLK_TC_ACT(BLK_TC_PC))
+               return;
+
+       /*
+        * should not happen, need to look into that...
+        */
+       if (!t->bytes)
+               return;
+
+       rw = (t->action & BLK_TC_ACT(BLK_TC_WRITE)) != 0;
+       ios[rw]++;
+       td->o.size += t->bytes;
+       store_ipo(td, t->sector, t->bytes, rw, ttime);
+}
+
+/*
+ * Load a blktrace file by reading all the blk_io_trace entries, and storing
+ * them as io_pieces like the fio text version would do.
+ */
 int load_blktrace(struct thread_data *td, const char *filename)
 {
+       unsigned long long ttime;
        struct blk_io_trace t;
+       unsigned long ios[2];
        int fd;
 
        fd = open(filename, O_RDONLY);
@@ -61,35 +121,68 @@ int load_blktrace(struct thread_data *td, const char *filename)
                return 1;
        }
 
+       td->o.size = 0;
+
+       ios[0] = ios[1] = 0;
+       ttime = 0;
        do {
+               /*
+                * Once this is working fully, I'll add a layer between
+                * here and read to cache trace data. Then we can avoid
+                * doing itsy bitsy reads, but instead pull in a larger
+                * chunk of data at the time.
+                */
                int ret = read(fd, &t, sizeof(t));
 
                if (ret < 0) {
                        td_verror(td, errno, "read blktrace file");
-                       return 1;
+                       goto err;
                } else if (!ret) {
                        break;
                } else if (ret != sizeof(t)) {
                        log_err("fio: short read on blktrace file\n");
-                       return 1;
+                       goto err;
                }
 
                if ((t.magic & 0xffffff00) != BLK_IO_TRACE_MAGIC) {
                        log_err("fio: bad magic in blktrace data\n");
-                       return 1;
+                       goto err;
                }
                if ((t.magic & 0xff) != BLK_IO_TRACE_VERSION) {
                        log_err("fio: bad blktrace version %d\n", t.magic & 0xff);
-                       return 1;
+                       goto err;
                }
                ret = discard_pdu(fd, &t);
                if (ret) {
                        td_verror(td, ret, "blktrace lseek");
-                       return 1;
+                       goto err;
                }
-               handle_trace(td, &t);
+               if (!ttime)
+                       ttime = t.time;
+               handle_trace(td, &t, t.time - ttime, ios);
+               ttime = t.time;
        } while (1);
 
        close(fd);
+
+       if (!ios[DDIR_READ] && !ios[DDIR_WRITE]) {
+               log_err("fio: found no ios in blktrace data\n");
+               return 1;
+       } else if (ios[DDIR_READ] && !ios[DDIR_READ])
+               td->o.td_ddir = TD_DDIR_READ;
+       else if (!ios[DDIR_READ] && ios[DDIR_WRITE])
+               td->o.td_ddir = TD_DDIR_WRITE;
+       else
+               td->o.td_ddir = TD_DDIR_RW;
+
+       /*
+        * We need to do direct/raw ios to the device, to avoid getting
+        * read-ahead in our way.
+        */
+       td->o.odirect = 1;
+
        return 0;
+err:
+       close(fd);
+       return 1;
 }