mirror_zfs/config/kernel-blk-queue-flush.m4
Brian Behlendorf 608f8749a1
Perform KABI checks in parallel
Reduce the time required for ./configure to perform the needed
KABI checks by allowing kbuild to compile multiple test cases in
parallel.  This was accomplished by splitting each test's source
code from the logic handling whether that code could be compiled
or not.

By introducing this split it's possible to minimize the number of
times kbuild needs to be invoked.  As importantly, it means all of
the tests can be built in parallel.  This does require a little extra
care since we expect some tests to fail, so the --keep-going (-k)
option must be provided otherwise some tests may not get compiled.
Furthermore, since a failure during the kbuild modpost phase will
result in an early exit; the final linking phase is limited to tests
which passed the initial compilation and produced an object file.

Once everything has been built the configure script proceeds as
previously.  The only significant difference is that it now merely
needs to test for the existence of a .ko file to determine the
result of a given test.  This vastly speeds up the entire process.

New test cases should use ZFS_LINUX_TEST_SRC to declare their test
source code and ZFS_LINUX_TEST_RESULT to check the result.  All of
the existing kernel-*.m4 files have been updated accordingly, see
config/kernel-current-time.m4 for a basic example.  The legacy
ZFS_LINUX_TRY_COMPILE macro has been kept to handle special cases
but it's use is not encouraged.

                  master (secs)   patched (secs)
                  -------------   ----------------
autogen.sh        61              68
configure         137             24  (~17% of current run time)
make -j $(nproc)  44              44
make rpms         287             150

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #8547 
Closes #9132
Closes #9341
2019-10-01 12:50:34 -07:00

70 lines
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dnl #
dnl # 2.6.36 API change
dnl # In 2.6.36 kernels the blk_queue_ordered() interface has been
dnl # replaced by the simpler blk_queue_flush(). However, while the
dnl # old interface was available to all the new one is GPL-only.
dnl # Thus in addition to detecting if this function is available
dnl # we determine if it is GPL-only. If the GPL-only interface is
dnl # there we implement our own compatibility function, otherwise
dnl # we use the function. The hope is that long term this function
dnl # will be opened up.
dnl #
AC_DEFUN([ZFS_AC_KERNEL_SRC_BLK_QUEUE_FLUSH], [
ZFS_LINUX_TEST_SRC([blk_queue_flush], [
#include <linux/blkdev.h>
], [
struct request_queue *q = NULL;
(void) blk_queue_flush(q, REQ_FLUSH);
], [$NO_UNUSED_BUT_SET_VARIABLE], [$ZFS_META_LICENSE])
ZFS_LINUX_TEST_SRC([blk_queue_write_cache], [
#include <linux/kernel.h>
#include <linux/blkdev.h>
], [
struct request_queue *q = NULL;
blk_queue_write_cache(q, true, true);
], [$NO_UNUSED_BUT_SET_VARIABLE], [$ZFS_META_LICENSE])
])
AC_DEFUN([ZFS_AC_KERNEL_BLK_QUEUE_FLUSH], [
AC_MSG_CHECKING([whether blk_queue_flush() is available])
ZFS_LINUX_TEST_RESULT([blk_queue_flush], [
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_BLK_QUEUE_FLUSH, 1,
[blk_queue_flush() is available])
AC_MSG_CHECKING([whether blk_queue_flush() is GPL-only])
ZFS_LINUX_TEST_RESULT([blk_queue_flush_license], [
AC_MSG_RESULT(no)
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_BLK_QUEUE_FLUSH_GPL_ONLY, 1,
[blk_queue_flush() is GPL-only])
])
],[
AC_MSG_RESULT(no)
])
dnl #
dnl # 4.7 API change
dnl # Replace blk_queue_flush with blk_queue_write_cache
dnl #
AC_MSG_CHECKING([whether blk_queue_write_cache() exists])
ZFS_LINUX_TEST_RESULT([blk_queue_write_cache], [
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_BLK_QUEUE_WRITE_CACHE, 1,
[blk_queue_write_cache() exists])
AC_MSG_CHECKING([whether blk_queue_write_cache() is GPL-only])
ZFS_LINUX_TEST_RESULT([blk_queue_write_cache_license], [
AC_MSG_RESULT(no)
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_BLK_QUEUE_WRITE_CACHE_GPL_ONLY, 1,
[blk_queue_write_cache() is GPL-only])
])
],[
AC_MSG_RESULT(no)
])
])