freebsd-dev/config/kernel-blk-queue-unplug.m4
Isaac Huang e8ac4557af Explicit block device plugging when submitting multiple BIOs
Without plugging, the default 'noop' scheduler will not merge
the BIOs which are part of a large ZIO.

Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Isaac Huang <he.huang@intel.com>
Closes #5181
2016-09-29 13:13:31 -07:00

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dnl #
dnl # 2.6.32-2.6.35 API - The BIO_RW_UNPLUG enum can be used as a hint
dnl # to unplug the queue.
dnl #
AC_DEFUN([ZFS_AC_KERNEL_BLK_QUEUE_HAVE_BIO_RW_UNPLUG], [
AC_MSG_CHECKING([whether the BIO_RW_UNPLUG enum is available])
tmp_flags="$EXTRA_KCFLAGS"
EXTRA_KCFLAGS="${NO_UNUSED_BUT_SET_VARIABLE}"
ZFS_LINUX_TRY_COMPILE([
#include <linux/blkdev.h>
],[
extern enum bio_rw_flags rw;
rw = BIO_RW_UNPLUG;
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_BLK_QUEUE_HAVE_BIO_RW_UNPLUG, 1,
[BIO_RW_UNPLUG is available])
],[
AC_MSG_RESULT(no)
])
EXTRA_KCFLAGS="$tmp_flags"
])
AC_DEFUN([ZFS_AC_KERNEL_BLK_QUEUE_HAVE_BLK_PLUG], [
AC_MSG_CHECKING([whether struct blk_plug is available])
tmp_flags="$EXTRA_KCFLAGS"
EXTRA_KCFLAGS="${NO_UNUSED_BUT_SET_VARIABLE}"
ZFS_LINUX_TRY_COMPILE([
#include <linux/blkdev.h>
],[
struct blk_plug plug;
blk_start_plug(&plug);
blk_finish_plug(&plug);
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_BLK_QUEUE_HAVE_BLK_PLUG, 1,
[struct blk_plug is available])
],[
AC_MSG_RESULT(no)
])
EXTRA_KCFLAGS="$tmp_flags"
])