Improve ZVOL queue behavior.

[zfs.git] / config / kernel-blk-queue-nonrot.m4

diff --git a/config/kernel-blk-queue-nonrot.m4 b/config/kernel-blk-queue-nonrot.m4
new file mode 100644 (file)
index 0000000..45d78f7
--- /dev/null
+++ b/config/kernel-blk-queue-nonrot.m4
@@ -0,0 +1,25 @@
+dnl #
+dnl # 2.6.27 API change
+dnl # The blk_queue_nonrot() function and QUEUE_FLAG_NONROT flag were
+dnl # added so non-rotational devices could be identified.  These devices
+dnl # have no seek time which the higher level elevator uses to optimize
+dnl # how the I/O issued to the device.
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_BLK_QUEUE_NONROT], [
+       AC_MSG_CHECKING([whether blk_queue_nonrot() is available])
+       tmp_flags="$EXTRA_KCFLAGS"
+       EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
+       ZFS_LINUX_TRY_COMPILE([
+               #include <linux/blkdev.h>
+       ],[
+               struct request_queue *q = NULL;
+               (void) blk_queue_nonrot(q);
+       ],[
+               AC_MSG_RESULT(yes)
+               AC_DEFINE(HAVE_BLK_QUEUE_NONROT, 1,
+                         [blk_queue_nonrot() is available])
+       ],[
+               AC_MSG_RESULT(no)
+       ])
+       EXTRA_KCFLAGS="$tmp_flags"
+])