BTW. I would be interested if this patch improves performance for you. Could you test it? (you also need my previous patch posted here https://www.redhat.com/archives/dm-devel/2020-January/msg00027.html ) Mikulas dm-writecache: use REQ_FUA when writing the superblock When writing the superblock, it may be better to submit just one I/O with the FUA bit set instead of two I/Os. Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> --- drivers/md/dm-writecache.c | 29 +++++++++++++++-------------- 1 file changed, 15 insertions(+), 14 deletions(-) Index: linux-2.6/drivers/md/dm-writecache.c =================================================================== --- linux-2.6.orig/drivers/md/dm-writecache.c 2020-01-08 17:56:41.000000000 +0100 +++ linux-2.6/drivers/md/dm-writecache.c 2020-01-08 17:56:49.000000000 +0100 @@ -448,7 +448,7 @@ static void writecache_wait_for_ios(stru !atomic_read(&wc->bio_in_progress[direction])); } -static void ssd_commit_flushed(struct dm_writecache *wc, bool wait_for_ios) +static void ssd_commit_flushed(struct dm_writecache *wc, bool wait_for_ios, bool use_fua) { struct dm_io_region region; struct dm_io_request req; @@ -479,7 +479,7 @@ static void ssd_commit_flushed(struct dm region.sector += wc->start_sector; atomic_inc(&endio.count); req.bi_op = REQ_OP_WRITE; - req.bi_op_flags = REQ_SYNC; + req.bi_op_flags = REQ_SYNC | (use_fua ? REQ_FUA : 0); req.mem.type = DM_IO_VMA; req.mem.ptr.vma = (char *)wc->memory_map + (size_t)i * BITMAP_GRANULARITY; req.client = wc->dm_io; @@ -497,17 +497,18 @@ static void ssd_commit_flushed(struct dm if (wait_for_ios) writecache_wait_for_ios(wc, WRITE); - writecache_disk_flush(wc, wc->ssd_dev); + if (!use_fua) + writecache_disk_flush(wc, wc->ssd_dev); memset(wc->dirty_bitmap, 0, wc->dirty_bitmap_size); } -static void writecache_commit_flushed(struct dm_writecache *wc, bool wait_for_ios) +static void writecache_commit_flushed(struct dm_writecache *wc, bool wait_for_ios, bool use_fua) { if (WC_MODE_PMEM(wc)) wmb(); else - ssd_commit_flushed(wc, wait_for_ios); + ssd_commit_flushed(wc, wait_for_ios, use_fua); } static void writecache_disk_flush(struct dm_writecache *wc, struct dm_dev *dev) @@ -727,12 +728,12 @@ static void writecache_flush(struct dm_w e = e2; cond_resched(); } - writecache_commit_flushed(wc, true); + writecache_commit_flushed(wc, true, false); wc->seq_count++; pmem_assign(sb(wc)->seq_count, cpu_to_le64(wc->seq_count)); writecache_flush_region(wc, &sb(wc)->seq_count, sizeof sb(wc)->seq_count); - writecache_commit_flushed(wc, false); + writecache_commit_flushed(wc, false, true); wc->overwrote_committed = false; @@ -756,7 +757,7 @@ static void writecache_flush(struct dm_w } if (need_flush_after_free) - writecache_commit_flushed(wc, false); + writecache_commit_flushed(wc, false, false); } static void writecache_flush_work(struct work_struct *work) @@ -809,7 +810,7 @@ static void writecache_discard(struct dm } if (discarded_something) - writecache_commit_flushed(wc, false); + writecache_commit_flushed(wc, false, false); } static bool writecache_wait_for_writeback(struct dm_writecache *wc) @@ -958,7 +959,7 @@ erase_this: if (need_flush) { writecache_flush_all_metadata(wc); - writecache_commit_flushed(wc, false); + writecache_commit_flushed(wc, false, false); } wc_unlock(wc); @@ -1342,7 +1343,7 @@ static void __writecache_endio_pmem(stru wc->writeback_size--; n_walked++; if (unlikely(n_walked >= ENDIO_LATENCY)) { - writecache_commit_flushed(wc, false); + writecache_commit_flushed(wc, false, false); wc_unlock(wc); wc_lock(wc); n_walked = 0; @@ -1423,7 +1424,7 @@ pop_from_list: writecache_wait_for_ios(wc, READ); } - writecache_commit_flushed(wc, false); + writecache_commit_flushed(wc, false, false); wc_unlock(wc); } @@ -1766,10 +1767,10 @@ static int init_memory(struct dm_writeca write_original_sector_seq_count(wc, &wc->entries[b], -1, -1); writecache_flush_all_metadata(wc); - writecache_commit_flushed(wc, false); + writecache_commit_flushed(wc, false, false); pmem_assign(sb(wc)->magic, cpu_to_le32(MEMORY_SUPERBLOCK_MAGIC)); writecache_flush_region(wc, &sb(wc)->magic, sizeof sb(wc)->magic); - writecache_commit_flushed(wc, false); + writecache_commit_flushed(wc, false, false); return 0; } -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
