libblock: Add read-ahead task

Read-ahead requests were previously executed in the context of the
reading task.  This blocks the reading task until the complete read
with read-ahead transfer is finished.  A read-ahead task is introduced
to off-load the read-ahead transfer.  This allows the reading task to
work with the requested block more quickly.  The read-ahead is triggered
after two misses of ascending consecutive blocks or a read hit of a
block read by the most-recent read-ahead transfer.  The read-ahead
feature is configurable and can be disabled.

6 files changed, 275 insertions, 0 deletions

diff --git a/testsuites/libtests/Makefile.am b/testsuites/libtests/Makefile.am
index 1274f2637b..9747ad19c6 100644
--- a/testsuites/libtests/Makefile.am
+++ b/testsuites/libtests/Makefile.am
@@ -1,6 +1,7 @@
 ACLOCAL_AMFLAGS = -I ../aclocal
 
 SUBDIRS = POSIX
+SUBDIRS += block13
 SUBDIRS += rbheap01
 SUBDIRS += flashdisk01
 
diff --git a/testsuites/libtests/block13/Makefile.am b/testsuites/libtests/block13/Makefile.am
new file mode 100644
index 0000000000..9b4a76d0eb
--- /dev/null
+++ b/testsuites/libtests/block13/Makefile.am
@@ -0,0 +1,19 @@
+rtems_tests_PROGRAMS = block13
+block13_SOURCES = init.c
+
+dist_rtems_tests_DATA = block13.scn block13.doc
+
+include $(RTEMS_ROOT)/make/custom/@RTEMS_BSP@.cfg
+include $(top_srcdir)/../automake/compile.am
+include $(top_srcdir)/../automake/leaf.am
+
+AM_CPPFLAGS += -I$(top_srcdir)/../support/include
+
+LINK_OBJS = $(block13_OBJECTS)
+LINK_LIBS = $(block13_LDLIBS)
+
+block13$(EXEEXT): $(block13_OBJECTS) $(block13_DEPENDENCIES)
+	@rm -f block13$(EXEEXT)
+	$(make-exe)
+
+include $(top_srcdir)/../automake/local.am
diff --git a/testsuites/libtests/block13/block13.doc b/testsuites/libtests/block13/block13.doc
new file mode 100644
index 0000000000..04fc066ada
--- /dev/null
+++ b/testsuites/libtests/block13/block13.doc
@@ -0,0 +1,11 @@
+This file describes the directives and concepts tested by this test set.
+
+test set name: block13
+
+directives:
+
+  TBD
+
+concepts:
+
+  Tests the read-ahead feature of bdbuf.
diff --git a/testsuites/libtests/block13/block13.scn b/testsuites/libtests/block13/block13.scn
new file mode 100644
index 0000000000..8cce71806d
--- /dev/null
+++ b/testsuites/libtests/block13/block13.scn
@@ -0,0 +1,11 @@
+*** TEST BLOCK 13 ***
+0 2 3 4 5 6 7 8 
+reset
+8 
+reset
+7 
+reset
+6 7 
+reset
+5 6 8 
+*** END OF TEST BLOCK 13 ***
diff --git a/testsuites/libtests/block13/init.c b/testsuites/libtests/block13/init.c
new file mode 100644
index 0000000000..43ce38860e
--- /dev/null
+++ b/testsuites/libtests/block13/init.c
@@ -0,0 +1,232 @@
+/*
+ * Copyright (c) 2012 embedded brains GmbH.  All rights reserved.
+ *
+ *  embedded brains GmbH
+ *  Obere Lagerstr. 30
+ *  82178 Puchheim
+ *  Germany
+ *  <rtems@embedded-brains.de>
+ *
+ * The license and distribution terms for this file may be
+ * found in the file LICENSE in this distribution or at
+ * http://www.rtems.com/license/LICENSE.
+ */
+
+#ifdef HAVE_CONFIG_H
+  #include "config.h"
+#endif
+
+#include "tmacros.h"
+
+#include <errno.h>
+#include <string.h>
+
+#include <rtems/blkdev.h>
+#include <rtems/bdbuf.h>
+
+#define BLOCK_COUNT 9
+#define READ_COUNT 19
+
+static int block_access_counts [BLOCK_COUNT];
+
+#define RESET_CACHE (-1)
+
+static const int action_sequence [READ_COUNT] = {
+  0, 2, 3, 4, 5, 6, 7, 8,
+  RESET_CACHE,
+  8,
+  RESET_CACHE,
+  7,
+  RESET_CACHE,
+  6, 7,
+  RESET_CACHE,
+  5, 6, 8
+};
+
+#define UNUSED_LINE { 0, 0, 0, 0, 0, 0, 0, 0, 0 }
+
+static int expected_block_access_counts [READ_COUNT] [BLOCK_COUNT] = {
+   { 1, 0, 0, 0, 0, 0, 0, 0, 0 },
+   { 1, 0, 1, 0, 0, 0, 0, 0, 0 },
+   { 1, 0, 1, 1, 1, 1, 0, 0, 0 },
+   { 1, 0, 1, 1, 1, 1, 0, 0, 0 },
+   { 1, 0, 1, 1, 1, 1, 1, 1, 0 },
+   { 1, 0, 1, 1, 1, 1, 1, 1, 0 },
+   { 1, 0, 1, 1, 1, 1, 1, 1, 1 },
+   { 1, 0, 1, 1, 1, 1, 1, 1, 1 },
+   UNUSED_LINE,
+   { 0, 0, 0, 0, 0, 0, 0, 0, 1 },
+   UNUSED_LINE,
+   { 0, 0, 0, 0, 0, 0, 0, 1, 0 },
+   UNUSED_LINE,
+   { 0, 0, 0, 0, 0, 0, 1, 0, 0 },
+   { 0, 0, 0, 0, 0, 0, 1, 1, 1 },
+   UNUSED_LINE,
+   { 0, 0, 0, 0, 0, 1, 0, 0, 0 },
+   { 0, 0, 0, 0, 0, 1, 1, 1, 1 },
+   { 0, 0, 0, 0, 0, 1, 1, 1, 1 }
+};
+
+#define NO_TRIGGER RTEMS_DISK_READ_AHEAD_NO_TRIGGER
+
+#define TRIGGER_AFTER_RESET RTEMS_DISK_READ_AHEAD_NO_TRIGGER
+
+static const rtems_blkdev_bnum trigger [READ_COUNT] = {
+  1, 3, 5, 5, 7, 7, NO_TRIGGER, NO_TRIGGER,
+  TRIGGER_AFTER_RESET,
+  9,
+  TRIGGER_AFTER_RESET,
+  8,
+  TRIGGER_AFTER_RESET,
+  7, NO_TRIGGER,
+  TRIGGER_AFTER_RESET,
+  6, 8, NO_TRIGGER
+};
+
+#define NOT_CHANGED_BY_RESET(i) (i)
+
+static const rtems_blkdev_bnum next [READ_COUNT] = {
+  2, 4, 6, 6, 8, 8, 8, 8,
+  NOT_CHANGED_BY_RESET(8),
+  10,
+  NOT_CHANGED_BY_RESET(10),
+  9,
+  NOT_CHANGED_BY_RESET(9),
+  8, 8,
+  NOT_CHANGED_BY_RESET(8),
+  7, 9, 9
+};
+
+static int test_disk_ioctl(rtems_disk_device *dd, uint32_t req, void *arg)
+{
+  int rv = 0;
+
+  if (req == RTEMS_BLKIO_REQUEST) {
+    rtems_blkdev_request *breq = arg;
+    rtems_blkdev_sg_buffer *sg = breq->bufs;
+    uint32_t i;
+
+    rtems_test_assert(breq->req == RTEMS_BLKDEV_REQ_READ);
+
+    for (i = 0; i < breq->bufnum; ++i) {
+      rtems_blkdev_bnum block = sg [i].block;
+
+      rtems_test_assert(block < BLOCK_COUNT);
+
+      ++block_access_counts [block];
+    }
+
+    (*breq->req_done)(breq->done_arg, RTEMS_SUCCESSFUL);
+  } else {
+    errno = EINVAL;
+    rv = -1;
+  }
+
+  return rv;
+}
+
+static void test_read_ahead(rtems_disk_device *dd)
+{
+  int i;
+
+  for (i = 0; i < READ_COUNT; ++i) {
+    int action = action_sequence [i];
+
+    if (action != RESET_CACHE) {
+      rtems_blkdev_bnum block = (rtems_blkdev_bnum) action;
+      rtems_status_code sc;
+      rtems_bdbuf_buffer *bd;
+
+      printf("%i ", action);
+
+      sc = rtems_bdbuf_read(dd, block, &bd);
+      rtems_test_assert(sc == RTEMS_SUCCESSFUL);
+
+      sc = rtems_bdbuf_release(bd);
+      rtems_test_assert(sc == RTEMS_SUCCESSFUL);
+
+      rtems_test_assert(
+        memcmp(
+          block_access_counts,
+          expected_block_access_counts [i],
+          sizeof(block_access_counts)
+        ) == 0
+      );
+    } else {
+      printf("\nreset\n");
+
+      rtems_bdbuf_purge_dev(dd);
+      memset(&block_access_counts, 0, sizeof(block_access_counts));
+    }
+
+    rtems_test_assert(trigger [i] == dd->read_ahead.trigger);
+    rtems_test_assert(next [i] == dd->read_ahead.next);
+  }
+
+  printf("\n");
+}
+
+static void test(void)
+{
+  rtems_status_code sc;
+  dev_t dev = 0;
+  rtems_disk_device *dd;
+
+  sc = rtems_disk_io_initialize();
+  rtems_test_assert(sc == RTEMS_SUCCESSFUL);
+
+  sc = rtems_disk_create_phys(
+    dev,
+    1,
+    BLOCK_COUNT,
+    test_disk_ioctl,
+    NULL,
+    NULL
+  );
+  rtems_test_assert(sc == RTEMS_SUCCESSFUL);
+
+  dd = rtems_disk_obtain(dev);
+  rtems_test_assert(dd != NULL);
+
+  test_read_ahead(dd);
+
+  sc = rtems_disk_release(dd);
+  rtems_test_assert(sc == RTEMS_SUCCESSFUL);
+
+  sc = rtems_disk_delete(dev);
+  rtems_test_assert(sc == RTEMS_SUCCESSFUL);
+}
+
+static void Init(rtems_task_argument arg)
+{
+  puts("\n\n*** TEST BLOCK 13 ***");
+
+  test();
+
+  puts("*** END OF TEST BLOCK 13 ***");
+
+  rtems_test_exit(0);
+}
+
+#define CONFIGURE_APPLICATION_NEEDS_CLOCK_DRIVER
+#define CONFIGURE_APPLICATION_NEEDS_CONSOLE_DRIVER
+#define CONFIGURE_APPLICATION_NEEDS_LIBBLOCK
+
+#define CONFIGURE_BDBUF_BUFFER_MIN_SIZE 1
+#define CONFIGURE_BDBUF_BUFFER_MAX_SIZE 1
+#define CONFIGURE_BDBUF_CACHE_MEMORY_SIZE BLOCK_COUNT
+#define CONFIGURE_BDBUF_MAX_READ_AHEAD_BLOCKS 2
+#define CONFIGURE_BDBUF_READ_AHEAD_TASK_PRIORITY 1
+
+#define CONFIGURE_USE_IMFS_AS_BASE_FILESYSTEM
+
+#define CONFIGURE_MAXIMUM_TASKS 1
+
+#define CONFIGURE_RTEMS_INIT_TASKS_TABLE
+
+#define CONFIGURE_INIT_TASK_INITIAL_MODES RTEMS_DEFAULT_MODES
+#define CONFIGURE_INIT_TASK_PRIORITY 2
+
+#define CONFIGURE_INIT
+
+#include <rtems/confdefs.h>
diff --git a/testsuites/libtests/configure.ac b/testsuites/libtests/configure.ac
index f6af3b11cd..7df0520f87 100644
--- a/testsuites/libtests/configure.ac
+++ b/testsuites/libtests/configure.ac
@@ -41,6 +41,7 @@ AM_CONDITIONAL(NETTESTS,test "$rtems_cv_RTEMS_NETWORKING" = "yes")
 
 # Explicitly list all Makefiles here
 AC_CONFIG_FILES([Makefile
+block13/Makefile
 rbheap01/Makefile
 syscall01/Makefile
 flashdisk01/Makefile