Hi, This patch-series is based on the original RFC patch series:- https://www.spinics.net/lists/linux-block/msg47933.html. I've designed a rough testcase based on the information present in the mailing list archive for original RFC, it may need some corrections from the author. If anyone is interested, test results are at the end of this patch. Following is the original cover-letter :- Information about continuous extent placement may be useful for some block devices. Say, distributed network filesystems, which provide block device interface, may use this information for better blocks placement over the nodes in their cluster, and for better performance. Block devices, which map a file on another filesystem (loop), may request the same length extent on underlining filesystem for less fragmentation and for batching allocation requests. Also, hypervisors like QEMU may use this information for optimization of cluster allocations. This patchset introduces REQ_OP_ALLOCATE, which is going to be used for forwarding user's fallocate(0) requests into block device internals. It rather similar to existing REQ_OP_DISCARD, REQ_OP_WRITE_ZEROES, etc. The corresponding exported primitive is called blkdev_issue_allocate(). See [1/3] for the details. Patch [2/3] teaches loop driver to handle REQ_OP_ALLOCATE requests by calling fallocate(0). Patch [3/3] makes ext4 to notify a block device about fallocate(0). Here is a simple test I did: https://gist.github.com/tkhai/5b788651cdb74c1dbff3500745878856 I attached a file on ext4 to loop. Then, created ext4 partition on loop device and started the test in the partition. Direct-io is enabled on loop. The test fallocates 4G file and writes from some offset with given step, then it chooses another offset and repeats. After the test all the blocks in the file become written. The results shows that batching extents-assigning requests improves the performance: Before patchset: real ~ 1min 27sec After patchset: real ~ 1min 16sec (18% better) Ordinary fallocate() before writes improves the performance by batching the requests. These results just show, the same is in case of forwarding extents information to underlining filesystem. Regards, Chaitanya Changes from V1:- 1. Adjust series from using assign range or ASSIGN_RANGE to allocate or ALLOCATE. (Martin) 2. Add SECT_FROM_SB_BLK() and NSECTS_FROM_SB_NBLK() macros since it avoids weired line breaking and duplication of the code for sb_issue_discard(), sb_issue_zeroout() and sb_issue_allocate(). Should there be a prep patch for this ? Changes from RFC:- 1. Add missing plumbing for REQ_OP_ASSIGN_RANGE similar to write-zeores. 2. Add a prep patch to create a helper to submit payloadless bios. 3. Design a testcases around the description present in the cover-letter. Chaitanya Kulkarni (1): block: create payloadless issue bio helper Kirill Tkhai (3): block: Add support for REQ_OP_ALLOCATE loop: Forward REQ_OP_ALLOCATE into fallocate(0) ext4: Notify block device about alloc-assigned blk block/blk-core.c | 5 ++ block/blk-lib.c | 115 +++++++++++++++++++++++++++++++------- block/blk-merge.c | 21 +++++++ block/blk-settings.c | 19 +++++++ block/blk-zoned.c | 1 + block/bounce.c | 1 + drivers/block/loop.c | 5 ++ fs/ext4/ext4.h | 2 + fs/ext4/extents.c | 12 +++- include/linux/bio.h | 9 ++- include/linux/blk_types.h | 2 + include/linux/blkdev.h | 55 ++++++++++++++---- 12 files changed, 210 insertions(+), 37 deletions(-) -- 2.22.0
