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. Ted, can you please take the ext2 + ext4 patches through your tree? Dave, can you please take the rest through the XFS tree? Changes since v3: - Corrected dax iomap code namespace for functions defined in fs/dax.c. (Dave Chinner) - Added leading "dax" namespace to new static functions in fs/dax.c. (Dave Chinner) - Made all DAX PMD code in fs/dax.c conditionally compiled based on CONFIG_FS_DAX_PMD. Otherwise a stub in include/linux/dax.h that just returns VM_FAULT_FALLBACK will be used. (Dave Chinner) - Removed dynamic debugging messages from DAX PMD fault path. Debugging tracepoints will be added later to both the PTE and PMD paths via a later patch set. (Dave Chinner) - Added a comment to ext2_dax_vm_ops explaining why we don't support DAX PMD faults in ext2. (Dave Chinner) This was built upon xfs/for-next with PMD performance fixes from Toshi Kani and Dan Williams. Dan's patch has already been merged for v4.8, and Toshi's patches are currently queued in Andrew Morton's mm tree for v4.9 inclusion. Here is a tree containing my changes and all the fixes that I've been testing: https://git.kernel.org/cgit/linux/kernel/git/zwisler/linux.git/log/?h=dax_pmd_v4 This tree has passed xfstests for ext2, ext4 and XFS both with and without DAX, and has passed targeted testing where I inserted, removed and flushed DAX PTEs and PMDs in every combination I could think of. Previously reported performance numbers: In some simple mmap I/O testing with FIO the use of PMD faults more than doubles I/O performance as compared with PTE faults. Here is the FIO script I used for my testing: [global] bs=4k size=2G directory=/mnt/pmem0 ioengine=mmap [randrw] rw=randrw Here are the performance results with XFS using only pte faults: READ: io=1022.7MB, aggrb=557610KB/s, minb=557610KB/s, maxb=557610KB/s, mint=1878msec, maxt=1878msec WRITE: io=1025.4MB, aggrb=559084KB/s, minb=559084KB/s, maxb=559084KB/s, mint=1878msec, maxt=1878msec Here are performance numbers for that same test using PMD faults: READ: io=1022.7MB, aggrb=1406.7MB/s, minb=1406.7MB/s, maxb=1406.7MB/s, mint=727msec, maxt=727msec WRITE: io=1025.4MB, aggrb=1410.4MB/s, minb=1410.4MB/s, maxb=1410.4MB/s, mint=727msec, maxt=727msec This was done on a random lab machine with a PMEM device made from memmap'd RAM. To get XFS to use PMD faults, I did the following: mkfs.xfs -f -d su=2m,sw=1 /dev/pmem0 mount -o dax /dev/pmem0 /mnt/pmem0 xfs_io -c "extsize 2m" /mnt/pmem0 Ross Zwisler (12): ext4: allow DAX writeback for hole punch ext4: tell DAX the size of allocation holes dax: remove buffer_size_valid() ext2: remove support for DAX PMD faults dax: make 'wait_table' global variable static dax: consistent variable naming for DAX entries dax: coordinate locking for offsets in PMD range dax: remove dax_pmd_fault() dax: correct dax iomap code namespace dax: add struct iomap based DAX PMD support xfs: use struct iomap based DAX PMD fault path dax: remove "depends on BROKEN" from FS_DAX_PMD fs/Kconfig | 1 - fs/dax.c | 650 +++++++++++++++++++++++++++------------------------- fs/ext2/file.c | 35 +-- fs/ext4/inode.c | 7 +- fs/xfs/xfs_aops.c | 25 +- fs/xfs/xfs_aops.h | 3 - fs/xfs/xfs_file.c | 10 +- include/linux/dax.h | 48 +++- mm/filemap.c | 6 +- 9 files changed, 402 insertions(+), 383 deletions(-) -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
