1. 22 May, 2015 8 commits
  2. 20 May, 2015 9 commits
  3. 19 May, 2015 6 commits
  4. 18 May, 2015 2 commits
  5. 08 May, 2015 6 commits
    • Shaohua Li's avatar
      blk-mq: make plug work for mutiple disks and queues · 5b3f341f
      Shaohua Li authored
      Last patch makes plug work for multiple queue case. However it only
      works for single disk case, because it assumes only one request in the
      plug list. If a task is accessing multiple disks, eg MD/DM, the
      assumption is wrong. Let blk_attempt_plug_merge() record request from
      the same queue.
      
      V2: use NULL parameter in !mq case. Fix a bug. Add comments in
      blk_attempt_plug_merge to make it less (hopefully) confusion.
      
      Cc: Jens Axboe <axboe@fb.com>
      Cc: Christoph Hellwig <hch@lst.de>
      Signed-off-by: default avatarShaohua Li <shli@fb.com>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      5b3f341f
    • Shaohua Li's avatar
      blk-mq: do limited block plug for multiple queue case · f984df1f
      Shaohua Li authored
      plug is still helpful for workload with IO merge, but it can be harmful
      otherwise especially with multiple hardware queues, as there is
      (supposed) no lock contention in this case and plug can introduce
      latency. For multiple queues, we do limited plug, eg plug only if there
      is request merge. If a request doesn't have merge with following
      request, the requet will be dispatched immediately.
      
      V2: check blk_queue_nomerges() as suggested by Jeff.
      
      Cc: Jens Axboe <axboe@fb.com>
      Cc: Christoph Hellwig <hch@lst.de>
      Signed-off-by: default avatarShaohua Li <shli@fb.com>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      f984df1f
    • Shaohua Li's avatar
      blk-mq: avoid re-initialize request which is failed in direct dispatch · 239ad215
      Shaohua Li authored
      If we directly issue a request and it fails, we use
      blk_mq_merge_queue_io(). But we already assigned bio to a request in
      blk_mq_bio_to_request. blk_mq_merge_queue_io shouldn't run
      blk_mq_bio_to_request again.
      Signed-off-by: default avatarShaohua Li <shli@fb.com>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      239ad215
    • Jeff Moyer's avatar
      blk-mq: fix plugging in blk_sq_make_request · e6c4438b
      Jeff Moyer authored
      The following appears in blk_sq_make_request:
      
      	/*
      	 * If we have multiple hardware queues, just go directly to
      	 * one of those for sync IO.
      	 */
      
      We clearly don't have multiple hardware queues, here!  This comment was
      introduced with this commit 07068d5b (blk-mq: split make request
      handler for multi and single queue):
      
          We want slightly different behavior from them:
      
          - On single queue devices, we currently use the per-process plug
            for deferred IO and for merging.
      
          - On multi queue devices, we don't use the per-process plug, but
            we want to go straight to hardware for SYNC IO.
      
      The old code had this:
      
              use_plug = !is_flush_fua && ((q->nr_hw_queues == 1) || !is_sync);
      
      and that was converted to:
      
      	use_plug = !is_flush_fua && !is_sync;
      
      which is not equivalent.  For the single queue case, that second half of
      the && expression is always true.  So, what I think was actually inteded
      follows (and this more closely matches what is done in blk_queue_bio).
      
      V2: delete the 'likely', which should not be a big deal
      Signed-off-by: default avatarJeff Moyer <jmoyer@redhat.com>
      Signed-off-by: default avatarShaohua Li <shli@fb.com>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      e6c4438b
    • Shaohua Li's avatar
      sched: always use blk_schedule_flush_plug in io_schedule_out · 5596d0d5
      Shaohua Li authored
      block plug callback could sleep, so we introduce a parameter
      'from_schedule' and corresponding drivers can use it to destinguish a
      schedule plug flush or a plug finish. Unfortunately io_schedule_out
      still uses blk_flush_plug(). This causes below output (Note, I added a
      might_sleep() in raid1_unplug to make it trigger faster, but the whole
      thing doesn't matter if I add might_sleep). In raid1/10, this can cause
      deadlock.
      
      This patch makes io_schedule_out always uses blk_schedule_flush_plug.
      This should only impact drivers (as far as I know, raid 1/10) which are
      sensitive to the 'from_schedule' parameter.
      
      [  370.817949] ------------[ cut here ]------------
      [  370.817960] WARNING: CPU: 7 PID: 145 at ../kernel/sched/core.c:7306 __might_sleep+0x7f/0x90()
      [  370.817969] do not call blocking ops when !TASK_RUNNING; state=2 set at [<ffffffff81092fcf>] prepare_to_wait+0x2f/0x90
      [  370.817971] Modules linked in: raid1
      [  370.817976] CPU: 7 PID: 145 Comm: kworker/u16:9 Tainted: G        W       4.0.0+ #361
      [  370.817977] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140709_153802- 04/01/2014
      [  370.817983] Workqueue: writeback bdi_writeback_workfn (flush-9:1)
      [  370.817985]  ffffffff81cd83be ffff8800ba8cb298 ffffffff819dd7af 0000000000000001
      [  370.817988]  ffff8800ba8cb2e8 ffff8800ba8cb2d8 ffffffff81051afc ffff8800ba8cb2c8
      [  370.817990]  ffffffffa00061a8 000000000000041e 0000000000000000 ffff8800ba8cba28
      [  370.817993] Call Trace:
      [  370.817999]  [<ffffffff819dd7af>] dump_stack+0x4f/0x7b
      [  370.818002]  [<ffffffff81051afc>] warn_slowpath_common+0x8c/0xd0
      [  370.818004]  [<ffffffff81051b86>] warn_slowpath_fmt+0x46/0x50
      [  370.818006]  [<ffffffff81092fcf>] ? prepare_to_wait+0x2f/0x90
      [  370.818008]  [<ffffffff81092fcf>] ? prepare_to_wait+0x2f/0x90
      [  370.818010]  [<ffffffff810776ef>] __might_sleep+0x7f/0x90
      [  370.818014]  [<ffffffffa0000c03>] raid1_unplug+0xd3/0x170 [raid1]
      [  370.818024]  [<ffffffff81421d9a>] blk_flush_plug_list+0x8a/0x1e0
      [  370.818028]  [<ffffffff819e3550>] ? bit_wait+0x50/0x50
      [  370.818031]  [<ffffffff819e21b0>] io_schedule_timeout+0x130/0x140
      [  370.818033]  [<ffffffff819e3586>] bit_wait_io+0x36/0x50
      [  370.818034]  [<ffffffff819e31b5>] __wait_on_bit+0x65/0x90
      [  370.818041]  [<ffffffff8125b67c>] ? ext4_read_block_bitmap_nowait+0xbc/0x630
      [  370.818043]  [<ffffffff819e3550>] ? bit_wait+0x50/0x50
      [  370.818045]  [<ffffffff819e3302>] out_of_line_wait_on_bit+0x72/0x80
      [  370.818047]  [<ffffffff810935e0>] ? autoremove_wake_function+0x40/0x40
      [  370.818050]  [<ffffffff811de744>] __wait_on_buffer+0x44/0x50
      [  370.818053]  [<ffffffff8125ae80>] ext4_wait_block_bitmap+0xe0/0xf0
      [  370.818058]  [<ffffffff812975d6>] ext4_mb_init_cache+0x206/0x790
      [  370.818062]  [<ffffffff8114bc6c>] ? lru_cache_add+0x1c/0x50
      [  370.818064]  [<ffffffff81297c7e>] ext4_mb_init_group+0x11e/0x200
      [  370.818066]  [<ffffffff81298231>] ext4_mb_load_buddy+0x341/0x360
      [  370.818068]  [<ffffffff8129a1a3>] ext4_mb_find_by_goal+0x93/0x2f0
      [  370.818070]  [<ffffffff81295b54>] ? ext4_mb_normalize_request+0x1e4/0x5b0
      [  370.818072]  [<ffffffff8129ab67>] ext4_mb_regular_allocator+0x67/0x460
      [  370.818074]  [<ffffffff81295b54>] ? ext4_mb_normalize_request+0x1e4/0x5b0
      [  370.818076]  [<ffffffff8129ca4b>] ext4_mb_new_blocks+0x4cb/0x620
      [  370.818079]  [<ffffffff81290956>] ext4_ext_map_blocks+0x4c6/0x14d0
      [  370.818081]  [<ffffffff812a4d4e>] ? ext4_es_lookup_extent+0x4e/0x290
      [  370.818085]  [<ffffffff8126399d>] ext4_map_blocks+0x14d/0x4f0
      [  370.818088]  [<ffffffff81266fbd>] ext4_writepages+0x76d/0xe50
      [  370.818094]  [<ffffffff81149691>] do_writepages+0x21/0x50
      [  370.818097]  [<ffffffff811d5c00>] __writeback_single_inode+0x60/0x490
      [  370.818099]  [<ffffffff811d630a>] writeback_sb_inodes+0x2da/0x590
      [  370.818103]  [<ffffffff811abf4b>] ? trylock_super+0x1b/0x50
      [  370.818105]  [<ffffffff811abf4b>] ? trylock_super+0x1b/0x50
      [  370.818107]  [<ffffffff811d665f>] __writeback_inodes_wb+0x9f/0xd0
      [  370.818109]  [<ffffffff811d69db>] wb_writeback+0x34b/0x3c0
      [  370.818111]  [<ffffffff811d70df>] bdi_writeback_workfn+0x23f/0x550
      [  370.818116]  [<ffffffff8106bbd8>] process_one_work+0x1c8/0x570
      [  370.818117]  [<ffffffff8106bb5b>] ? process_one_work+0x14b/0x570
      [  370.818119]  [<ffffffff8106c09b>] worker_thread+0x11b/0x470
      [  370.818121]  [<ffffffff8106bf80>] ? process_one_work+0x570/0x570
      [  370.818124]  [<ffffffff81071868>] kthread+0xf8/0x110
      [  370.818126]  [<ffffffff81071770>] ? kthread_create_on_node+0x210/0x210
      [  370.818129]  [<ffffffff819e9322>] ret_from_fork+0x42/0x70
      [  370.818131]  [<ffffffff81071770>] ? kthread_create_on_node+0x210/0x210
      [  370.818132] ---[ end trace 7b4deb71e68b6605 ]---
      
      V2: don't change ->in_iowait
      
      Cc: NeilBrown <neilb@suse.de>
      Signed-off-by: default avatarShaohua Li <shli@fb.com>
      Reviewed-by: default avatarJeff Moyer <jmoyer@redhat.com>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      5596d0d5
    • Shaohua Li's avatar
      blk: clean up plug · dd6cf3e1
      Shaohua Li authored
      Current code looks like inner plug gets flushed with a
      blk_finish_plug(). Actually it's a nop. All requests/callbacks are added
      to current->plug, while only outmost plug is assigned to current->plug.
      So inner plug always has empty request/callback list, which makes
      blk_flush_plug_list() a nop. This tries to make the code more clear.
      Signed-off-by: default avatarShaohua Li <shli@fb.com>
      Reviewed-by: default avatarJeff Moyer <jmoyer@redhat.com>
      Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      dd6cf3e1
  6. 05 May, 2015 9 commits