Hi Mike Some times ago, I sent this patch as dm-bufio optimization (it doesn't have to write full buffers, it only writes a part of the buffer that changed). You delayed the patch until the next kernel.
Will you submit the patch to the current kernel? Mikulas ---------- Forwarded message ---------- Date: Sun, 30 Apr 2017 17:31:22 -0400 (EDT) From: Mikulas Patocka <[email protected]> To: Mike Snitzer <[email protected]> Subject: [PATCH] an optimization for dm-bufio and dm-integrity Hi This is an optimization for dm-bufio and dm-integrity, so that it can write only part of the buffer. Signed-off-by: Mikulas Patocka <[email protected]> --- drivers/md/dm-bufio.c | 95 ++++++++++++++++++++++++++++++++-------------- drivers/md/dm-bufio.h | 9 ++++ drivers/md/dm-integrity.c | 2 3 files changed, 77 insertions(+), 29 deletions(-) Index: linux-2.6/drivers/md/dm-bufio.c =================================================================== --- linux-2.6.orig/drivers/md/dm-bufio.c +++ linux-2.6/drivers/md/dm-bufio.c @@ -64,6 +64,12 @@ #define DM_BUFIO_BLOCK_SIZE_GFP_LIMIT (PAGE_SIZE << (MAX_ORDER - 1)) /* + * Align buffer writes to this boundary. + * Tests show that SSDs have the highest IOPS when using 4k writes. + */ +#define DM_BUFIO_WRITE_ALIGN 4096 + +/* * dm_buffer->list_mode */ #define LIST_CLEAN 0 @@ -149,6 +155,10 @@ struct dm_buffer { int write_error; unsigned long state; unsigned long last_accessed; + unsigned dirty_start; + unsigned dirty_end; + unsigned write_start; + unsigned write_end; struct dm_bufio_client *c; struct list_head write_list; struct bio bio; @@ -560,7 +570,7 @@ static void dmio_complete(unsigned long } static void use_dmio(struct dm_buffer *b, int rw, sector_t sector, - unsigned n_sectors, bio_end_io_t *end_io) + unsigned n_sectors, unsigned offset, bio_end_io_t *end_io) { int r; struct dm_io_request io_req = { @@ -578,10 +588,10 @@ static void use_dmio(struct dm_buffer *b if (b->data_mode != DATA_MODE_VMALLOC) { io_req.mem.type = DM_IO_KMEM; - io_req.mem.ptr.addr = b->data; + io_req.mem.ptr.addr = (char *)b->data + offset; } else { io_req.mem.type = DM_IO_VMA; - io_req.mem.ptr.vma = b->data; + io_req.mem.ptr.vma = (char *)b->data + offset; } b->bio.bi_end_io = end_io; @@ -609,10 +619,10 @@ static void inline_endio(struct bio *bio } static void use_inline_bio(struct dm_buffer *b, int rw, sector_t sector, - unsigned n_sectors, bio_end_io_t *end_io) + unsigned n_sectors, unsigned offset, bio_end_io_t *end_io) { char *ptr; - int len; + unsigned len; bio_init(&b->bio, b->bio_vec, DM_BUFIO_INLINE_VECS); b->bio.bi_iter.bi_sector = sector; @@ -625,29 +635,20 @@ static void use_inline_bio(struct dm_buf b->bio.bi_private = end_io; bio_set_op_attrs(&b->bio, rw, 0); - /* - * We assume that if len >= PAGE_SIZE ptr is page-aligned. - * If len < PAGE_SIZE the buffer doesn't cross page boundary. - */ - ptr = b->data; + ptr = (char *)b->data + offset; len = n_sectors << SECTOR_SHIFT; - if (len >= PAGE_SIZE) - BUG_ON((unsigned long)ptr & (PAGE_SIZE - 1)); - else - BUG_ON((unsigned long)ptr & (len - 1)); - do { - if (!bio_add_page(&b->bio, virt_to_page(ptr), - len < PAGE_SIZE ? len : PAGE_SIZE, + unsigned this_step = min((unsigned)(PAGE_SIZE - offset_in_page(ptr)), len); + if (!bio_add_page(&b->bio, virt_to_page(ptr), this_step, offset_in_page(ptr))) { BUG_ON(b->c->block_size <= PAGE_SIZE); - use_dmio(b, rw, sector, n_sectors, end_io); + use_dmio(b, rw, sector, n_sectors, offset, end_io); return; } - len -= PAGE_SIZE; - ptr += PAGE_SIZE; + len -= this_step; + ptr += this_step; } while (len > 0); submit_bio(&b->bio); @@ -657,18 +658,33 @@ static void submit_io(struct dm_buffer * { unsigned n_sectors; sector_t sector; - - if (rw == WRITE && b->c->write_callback) - b->c->write_callback(b); + unsigned offset, end; sector = (b->block << b->c->sectors_per_block_bits) + b->c->start; - n_sectors = 1 << b->c->sectors_per_block_bits; + + if (rw != WRITE) { + n_sectors = 1 << b->c->sectors_per_block_bits; + offset = 0; + } else { + if (b->c->write_callback) + b->c->write_callback(b); + offset = b->write_start; + end = b->write_end; + offset &= -DM_BUFIO_WRITE_ALIGN; + end += DM_BUFIO_WRITE_ALIGN - 1; + end &= -DM_BUFIO_WRITE_ALIGN; + if (unlikely(end > b->c->block_size)) + end = b->c->block_size; + + sector += offset >> SECTOR_SHIFT; + n_sectors = (end - offset) >> SECTOR_SHIFT; + } if (n_sectors <= ((DM_BUFIO_INLINE_VECS * PAGE_SIZE) >> SECTOR_SHIFT) && b->data_mode != DATA_MODE_VMALLOC) - use_inline_bio(b, rw, sector, n_sectors, end_io); + use_inline_bio(b, rw, sector, n_sectors, offset, end_io); else - use_dmio(b, rw, sector, n_sectors, end_io); + use_dmio(b, rw, sector, n_sectors, offset, end_io); } /*---------------------------------------------------------------- @@ -719,6 +735,9 @@ static void __write_dirty_buffer(struct clear_bit(B_DIRTY, &b->state); wait_on_bit_lock_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); + b->write_start = b->dirty_start; + b->write_end = b->dirty_end; + if (!write_list) submit_io(b, WRITE, write_endio); else @@ -1219,19 +1238,37 @@ void dm_bufio_release(struct dm_buffer * } EXPORT_SYMBOL_GPL(dm_bufio_release); -void dm_bufio_mark_buffer_dirty(struct dm_buffer *b) +void dm_bufio_mark_partial_buffer_dirty(struct dm_buffer *b, + unsigned start, unsigned end) { struct dm_bufio_client *c = b->c; + BUG_ON(start >= end); + BUG_ON(end > b->c->block_size); + dm_bufio_lock(c); BUG_ON(test_bit(B_READING, &b->state)); - if (!test_and_set_bit(B_DIRTY, &b->state)) + if (!test_and_set_bit(B_DIRTY, &b->state)) { + b->dirty_start = start; + b->dirty_end = end; __relink_lru(b, LIST_DIRTY); + } else { + if (start < b->dirty_start) + b->dirty_start = start; + if (end > b->dirty_end) + b->dirty_end = end; + } dm_bufio_unlock(c); } +EXPORT_SYMBOL_GPL(dm_bufio_mark_partial_buffer_dirty); + +void dm_bufio_mark_buffer_dirty(struct dm_buffer *b) +{ + dm_bufio_mark_partial_buffer_dirty(b, 0, b->c->block_size); +} EXPORT_SYMBOL_GPL(dm_bufio_mark_buffer_dirty); void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c) @@ -1396,6 +1433,8 @@ retry: wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); set_bit(B_DIRTY, &b->state); + b->dirty_start = 0; + b->dirty_end = c->block_size; __unlink_buffer(b); __link_buffer(b, new_block, LIST_DIRTY); } else { Index: linux-2.6/drivers/md/dm-bufio.h =================================================================== --- linux-2.6.orig/drivers/md/dm-bufio.h +++ linux-2.6/drivers/md/dm-bufio.h @@ -94,6 +94,15 @@ void dm_bufio_release(struct dm_buffer * void dm_bufio_mark_buffer_dirty(struct dm_buffer *b); /* + * Mark a part of the buffer dirty. + * + * The specified part of the buffer is scheduled to be written. dm-bufio may + * write the specified part of the buffer or it may write a larger superset. + */ +void dm_bufio_mark_partial_buffer_dirty(struct dm_buffer *b, + unsigned start, unsigned end); + +/* * Initiate writing of dirty buffers, without waiting for completion. */ void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c); Index: linux-2.6/drivers/md/dm-integrity.c =================================================================== --- linux-2.6.orig/drivers/md/dm-integrity.c +++ linux-2.6/drivers/md/dm-integrity.c @@ -1039,7 +1039,7 @@ static int dm_integrity_rw_tag(struct dm memcpy(tag, dp, to_copy); } else if (op == TAG_WRITE) { memcpy(dp, tag, to_copy); - dm_bufio_mark_buffer_dirty(b); + dm_bufio_mark_partial_buffer_dirty(b, *metadata_offset, *metadata_offset + to_copy); } else { /* e.g.: op == TAG_CMP */ if (unlikely(memcmp(dp, tag, to_copy))) { -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
