On 2017.03.04 at 17:01 +0100, Paolo Valente wrote: > Hi, > at last, here is my first patch series meant for merging. It adds BFQ > to blk-mq. Don't worry, in this message I won't bore you again with > the wonderful properties of BFQ :) I gave BFQ a quick try. Unfortunately it hangs when I try to delete btrfs snapshots: root 124 0.0 0.0 0 0 ? D 07:19 0:03 [btrfs-cleaner] root 125 0.0 0.0 0 0 ? D 07:19 0:00 [btrfs-transacti] [ 4372.880116] sysrq: SysRq : Show Blocked State [ 4372.880125] task PC stack pid father [ 4372.880148] btrfs-cleaner D 0 124 2 0x00000000 [ 4372.880156] Call Trace: [ 4372.880166] ? __schedule+0x160/0x7c0 [ 4372.880174] ? io_schedule+0x64/0xe0 [ 4372.880179] ? wait_on_page_bit+0x7a/0x100 [ 4372.880183] ? devm_memunmap+0x40/0x40 [ 4372.880189] ? read_extent_buffer_pages+0x25c/0x2c0 [ 4372.880195] ? run_one_async_done+0xc0/0xc0 [ 4372.880200] ? btree_read_extent_buffer_pages+0x60/0x2e0 [ 4372.880206] ? read_tree_block+0x2c/0x60 [ 4372.880211] ? read_block_for_search.isra.38+0xec/0x3a0 [ 4372.880217] ? btrfs_search_slot+0x214/0xbc0 [ 4372.880221] ? lookup_inline_extent_backref+0xfb/0x8c0 [ 4372.880225] ? __btrfs_free_extent.isra.74+0xe9/0xdc0 [ 4372.880231] ? btrfs_merge_delayed_refs+0x57/0x6e0 [ 4372.880235] ? __btrfs_run_delayed_refs+0x60d/0x1340 [ 4372.880239] ? btrfs_run_delayed_refs+0x64/0x280 [ 4372.880243] ? btrfs_should_end_transaction+0x3b/0xa0 [ 4372.880247] ? btrfs_drop_snapshot+0x3b2/0x800 [ 4372.880251] ? __schedule+0x168/0x7c0 [ 4372.880254] ? btrfs_clean_one_deleted_snapshot+0xa4/0xe0 [ 4372.880259] ? cleaner_kthread+0x13a/0x180 [ 4372.880264] ? btree_invalidatepage+0xc0/0xc0 [ 4372.880268] ? kthread+0x144/0x180 [ 4372.880272] ? kthread_flush_work_fn+0x20/0x20 [ 4372.880277] ? ret_from_fork+0x23/0x30 [ 4372.880280] btrfs-transacti D 0 125 2 0x00000000 [ 4372.880285] Call Trace: [ 4372.880290] ? __schedule+0x160/0x7c0 [ 4372.880295] ? io_schedule+0x64/0xe0 [ 4372.880300] ? wait_on_page_bit_common.constprop.57+0x160/0x180 [ 4372.880303] ? devm_memunmap+0x40/0x40 [ 4372.880307] ? __filemap_fdatawait_range+0xd3/0x140 [ 4372.880311] ? clear_state_bit.constprop.82+0xf7/0x180 [ 4372.880315] ? __clear_extent_bit.constprop.79+0x138/0x3c0 [ 4372.880319] ? filemap_fdatawait_range+0x9/0x60 [ 4372.880323] ? __btrfs_wait_marked_extents.isra.18+0xc1/0x100 [ 4372.880327] ? btrfs_write_and_wait_marked_extents.constprop.23+0x49/0x80 [ 4372.880331] ? btrfs_commit_transaction+0x8e1/0xb00 [ 4372.880334] ? join_transaction.constprop.24+0x10/0xa0 [ 4372.880340] ? wake_bit_function+0x60/0x60 [ 4372.880345] ? transaction_kthread+0x185/0x1a0 [ 4372.880350] ? btrfs_cleanup_transaction+0x500/0x500 [ 4372.880354] ? kthread+0x144/0x180 [ 4372.880358] ? kthread_flush_work_fn+0x20/0x20 [ 4372.880362] ? ret_from_fork+0x23/0x30 [ 4372.880367] ntpd D 0 175 1 0x00000004 [ 4372.880372] Call Trace: [ 4372.880375] ? __schedule+0x160/0x7c0 [ 4372.880379] ? schedule_preempt_disabled+0x2d/0x80 [ 4372.880383] ? __mutex_lock.isra.5+0x17b/0x4c0 [ 4372.880386] ? wait_current_trans+0x15/0xc0 [ 4372.880391] ? btrfs_free_path+0xe/0x20 [ 4372.880395] ? btrfs_pin_log_trans+0x14/0x40 [ 4372.880400] ? btrfs_rename2+0x28e/0x19c0 [ 4372.880404] ? path_init+0x187/0x3e0 [ 4372.880407] ? unlazy_walk+0x4b/0x100 [ 4372.880410] ? terminate_walk+0x8d/0x100 [ 4372.880414] ? filename_parentat+0x1e9/0x2c0 [ 4372.880420] ? __kmalloc_track_caller+0xc4/0x100 [ 4372.880424] ? vfs_rename+0x33f/0x7e0 [ 4372.880428] ? SYSC_renameat2+0x53c/0x680 [ 4372.880433] ? entry_SYSCALL_64_fastpath+0x13/0x94 [ 4372.880437] fcron D 0 178 1 0x00000000 [ 4372.880441] Call Trace: [ 4372.880445] ? __schedule+0x160/0x7c0 [ 4372.880448] ? schedule_preempt_disabled+0x2d/0x80 [ 4372.880452] ? __mutex_lock.isra.5+0x17b/0x4c0 [ 4372.880458] ? pagevec_lookup_tag+0x18/0x20 [ 4372.880462] ? btrfs_log_dentry_safe+0x4cd/0xac0 [ 4372.880466] ? btrfs_start_transaction+0x249/0x460 [ 4372.880470] ? btrfs_sync_file+0x288/0x3c0 [ 4372.880475] ? btrfs_file_write_iter+0x3a9/0x4e0 [ 4372.880479] ? vfs_write+0x26c/0x2c0 [ 4372.880483] ? SyS_write+0x3d/0xa0 [ 4372.880486] ? SyS_fchown+0x7b/0xa0 [ 4372.880491] ? entry_SYSCALL_64_fastpath+0x13/0x94 [ 4372.880508] kworker/u8:8 D 0 759 2 0x00000000 [ 4372.880518] Workqueue: btrfs-submit btrfs_submit_helper [ 4372.880520] Call Trace: [ 4372.880524] ? __schedule+0x160/0x7c0 [ 4372.880529] ? io_schedule+0x64/0xe0 [ 4372.880534] ? blk_mq_get_tag+0x212/0x320 [ 4372.880538] ? wake_bit_function+0x60/0x60 [ 4372.880544] ? __blk_mq_alloc_request+0x11/0x1c0 [ 4372.880548] ? blk_mq_sched_get_request+0x17e/0x220 [ 4372.880553] ? blk_sq_make_request+0xd3/0x4c0 [ 4372.880557] ? blk_mq_sched_dispatch_requests+0x104/0x160 [ 4372.880561] ? generic_make_request+0xc3/0x2e0 [ 4372.880564] ? submit_bio+0x58/0x100 [ 4372.880569] ? run_scheduled_bios+0x1a6/0x500 [ 4372.880574] ? btrfs_worker_helper+0x129/0x1c0 [ 4372.880580] ? process_one_work+0x1bc/0x400 [ 4372.880585] ? worker_thread+0x42/0x540 [ 4372.880588] ? __schedule+0x168/0x7c0 [ 4372.880592] ? process_one_work+0x400/0x400 [ 4372.880596] ? kthread+0x144/0x180 [ 4372.880600] ? kthread_flush_work_fn+0x20/0x20 [ 4372.880605] ? ret_from_fork+0x23/0x30 I could get it going again by running: echo "mq-deadline" > /sys/block/sdb/queue/scheduler -- Markus
