On Wed, Aug 31, 2016 at 08:20:48PM +0000, Kani, Toshimitsu wrote:
On Tue, 2016-08-30 at 17:01 -0600, Ross Zwisler wrote:
> On Tue, Aug 23, 2016 at 04:04:10PM -0600, Ross Zwisler wrote:
> > DAX PMDs have been disabled since Jan Kara introduced DAX radix
> > tree based locking. This series allows DAX PMDs to participate in
> > the DAX radix tree based locking scheme so that they can be re-
> > enabled.
> > Changes since v1:
> > - PMD entry locking is now done based on the starting offset of
> > the PMD entry, rather than on the radix tree slot which was
> > unreliable. (Jan)
> > - Fixed the one issue I could find with hole punch. As far as I
> > can tell hole punch now works correctly for both PMD and PTE DAX
> > entries, 4k zero pages and huge zero pages.
> > - Fixed the way that ext2 returns the size of holes in
> > ext2_get_block(). (Jan)
> > - Made the 'wait_table' global variable static in respnse to a
> > sparse warning.
> > - Fixed some more inconsitent usage between the names 'ret' and
> > 'entry' for radix tree entry variables.
> > Ross Zwisler (9):
> > ext4: allow DAX writeback for hole punch
> > ext2: tell DAX the size of allocation holes
> > ext4: tell DAX the size of allocation holes
> > dax: remove buffer_size_valid()
> > dax: make 'wait_table' global variable static
> > dax: consistent variable naming for DAX entries
> > dax: coordinate locking for offsets in PMD range
> > dax: re-enable DAX PMD support
> > dax: remove "depends on BROKEN" from FS_DAX_PMD
> > fs/Kconfig | 1 -
> > fs/dax.c | 297 +++++++++++++++++++++++++++++-----------
> > ------------
> > fs/ext2/inode.c | 3 +
> > fs/ext4/inode.c | 7 +-
> > include/linux/dax.h | 29 ++++-
> > mm/filemap.c | 6 +-
> > 6 files changed, 201 insertions(+), 142 deletions(-)
> > --
> > 2.9.0
> Ping on this series? Any objections or comments?
I am seeing a major performance loss in fio mmap test with this patch-
set applied. This happens with or without my patches  applied on
top of yours. Without my patches, dax_pmd_fault() falls back to the
pte handler since an mmap'ed address is not 2MB-aligned.
I have attached three test results.
o rc4.log - 4.8.0-rc4 (base)
o non-pmd.log - 4.8.0-rc4 + your patchset (fall back to pte)
o pmd.log - 4.8.0-rc4 + your patchset + my patchset (use pmd maps)
My test steps are as follows.
mkfs.ext4 -O bigalloc -C 2M /dev/pmem0
mount -o dax /dev/pmem0 /mnt/pmem0
numactl --preferred block:pmem0 --cpunodebind block:pmem0 fio test.fio
Can you please take a look?
Yep, thanks for the report.