Hi Oliver, On Mon, May 05, 2014 at 11:00:13PM +0200, Oliver Winker wrote: > Hello, > > 1) Attached a full function-trace log + other SysRq outputs, see [1] > attached. > > I saw bdi_...() calls in the s2disk paths, but didn't check in detail > Probably more efficient when one of you guys looks directly. Thanks, this looks interesting. balance_dirty_pages() wakes up the bdi_wq workqueue as it should: [ 249.148009] s2disk-3327 2.... 48550413us : global_dirty_limits <-balance_dirty_pages_ratelimited [ 249.148009] s2disk-3327 2.... 48550414us : global_dirtyable_memory <-global_dirty_limits [ 249.148009] s2disk-3327 2.... 48550414us : writeback_in_progress <-balance_dirty_pages_ratelimited [ 249.148009] s2disk-3327 2.... 48550414us : bdi_start_background_writeback <-balance_dirty_pages_ratelimited [ 249.148009] s2disk-3327 2.... 48550414us : mod_delayed_work_on <-balance_dirty_pages_ratelimited [ 249.148009] s2disk-3327 2.... 48550414us : try_to_grab_pending <-mod_delayed_work_on [ 249.148009] s2disk-3327 2d... 48550414us : del_timer <-try_to_grab_pending [ 249.148009] s2disk-3327 2d... 48550415us : get_work_pool <-try_to_grab_pending [ 249.148009] s2disk-3327 2d... 48550415us : _raw_spin_lock <-try_to_grab_pending [ 249.148009] s2disk-3327 2d... 48550415us : get_work_pwq <-try_to_grab_pending [ 249.148009] s2disk-3327 2d... 48550415us : pwq_activate_delayed_work <-try_to_grab_pending [ 249.148009] s2disk-3327 2d... 48550415us : get_work_pwq <-pwq_activate_delayed_work [ 249.148009] s2disk-3327 2d... 48550415us : move_linked_works <-pwq_activate_delayed_work [ 249.148009] s2disk-3327 2d... 48550415us : get_work_pwq <-try_to_grab_pending [ 249.148009] s2disk-3327 2d... 48550416us : pwq_dec_nr_in_flight <-try_to_grab_pending [ 249.148009] s2disk-3327 2d... 48550416us : __queue_delayed_work <-mod_delayed_work_on [ 249.148009] s2disk-3327 2d... 48550416us : __queue_work <-mod_delayed_work_on [ 249.148009] s2disk-3327 2d... 48550416us : get_work_pool <-__queue_work [ 249.148009] s2disk-3327 2d... 48550416us : _raw_spin_lock <-__queue_work [ 249.148009] s2disk-3327 2d... 48550416us : insert_work <-__queue_work [ 249.148009] s2disk-3327 2d... 48550417us : get_pwq.isra.20 <-insert_work [ 249.148009] s2disk-3327 2d... 48550417us : wake_up_worker <-__queue_work [ 249.148009] s2disk-3327 2d... 48550417us : wake_up_process <-__queue_work [ 249.148009] s2disk-3327 2d... 48550417us : try_to_wake_up <-__queue_work [ 249.148009] s2disk-3327 2d... 48550417us : _raw_spin_lock_irqsave <-try_to_wake_up [ 249.148009] s2disk-3327 2d... 48550417us : task_waking_fair <-try_to_wake_up [ 249.148009] s2disk-3327 2d... 48550418us : select_task_rq_fair <-select_task_rq [ 249.148009] s2disk-3327 2d... 48550418us : idle_cpu <-select_task_rq_fair [ 249.148009] s2disk-3327 2d... 48550418us : idle_cpu <-select_task_rq_fair [ 249.148009] s2disk-3327 2d... 48550418us : cpus_share_cache <-try_to_wake_up [ 249.148009] s2disk-3327 2d... 48550418us : _raw_spin_lock <-try_to_wake_up [ 249.148009] s2disk-3327 2d... 48550419us : ttwu_do_activate.constprop.100 <-try_to_wake_up [ 249.148009] s2disk-3327 2d... 48550419us : activate_task <-ttwu_do_activate.constprop.100 [ 249.148009] s2disk-3327 2d... 48550419us : enqueue_task <-ttwu_do_activate.constprop.100 [ 249.148009] s2disk-3327 2d... 48550419us : update_rq_clock <-enqueue_task [ 249.148009] s2disk-3327 2d... 48550419us : enqueue_task_fair <-ttwu_do_activate.constprop.100 [ 249.148009] s2disk-3327 2d... 48550419us : update_curr <-enqueue_task_fair [ 249.148009] s2disk-3327 2d... 48550420us : update_min_vruntime <-update_curr [ 249.148009] s2disk-3327 2d... 48550420us : __compute_runnable_contrib.part.55 <-update_entity_load_avg [ 249.148009] s2disk-3327 2d... 48550420us : update_cfs_rq_blocked_load <-enqueue_task_fair [ 249.148009] s2disk-3327 2d... 48550420us : account_entity_enqueue <-enqueue_task_fair [ 249.148009] s2disk-3327 2d... 48550420us : update_cfs_shares <-enqueue_task_fair [ 249.148009] s2disk-3327 2d... 48550420us : __enqueue_entity <-enqueue_task_fair [ 249.148009] s2disk-3327 2d... 48550421us : hrtick_update <-ttwu_do_activate.constprop.100 [ 249.148009] s2disk-3327 2d... 48550421us : wq_worker_waking_up <-ttwu_do_activate.constprop.100 [ 249.148009] s2disk-3327 2d... 48550421us : kthread_data <-wq_worker_waking_up [ 249.148009] s2disk-3327 2d... 48550421us : ttwu_do_wakeup <-try_to_wake_up [ 249.148009] s2disk-3327 2d... 48550421us : check_preempt_curr <-ttwu_do_wakeup [ 249.148009] s2disk-3327 2d... 48550421us : check_preempt_wakeup <-check_preempt_curr [ 249.148009] s2disk-3327 2d... 48550422us : update_curr <-check_preempt_wakeup [ 249.148009] s2disk-3327 2d... 48550422us : wakeup_preempt_entity.isra.53 <-check_preempt_wakeup [ 249.148009] s2disk-3327 2d... 48550422us : _raw_spin_unlock_irqrestore <-try_to_wake_up [ 249.148009] s2disk-3327 2.... 48550423us : bdi_dirty_limit <-bdi_dirty_limits [ 249.148009] s2disk-3327 2d... 48550423us : _raw_spin_lock_irqsave <-__percpu_counter_sum [ 249.148009] s2disk-3327 2d... 48550423us : _raw_spin_unlock_irqrestore <-__percpu_counter_sum [ 249.148009] s2disk-3327 2d... 48550423us : _raw_spin_lock_irqsave <-__percpu_counter_sum [ 249.148009] s2disk-3327 2d... 48550424us : _raw_spin_unlock_irqrestore <-__percpu_counter_sum [ 249.148009] s2disk-3327 2.... 48550424us : bdi_position_ratio <-balance_dirty_pages_ratelimited [ 249.148009] s2disk-3327 2.... 48550424us : io_schedule_timeout <-balance_dirty_pages_ratelimited [ 249.148009] s2disk-3327 2.... 48550424us : __delayacct_blkio_start <-io_schedule_timeout [ 249.148009] s2disk-3327 2.... 48550424us : ktime_get_ts <-io_schedule_timeout [ 249.148009] s2disk-3327 2.... 48550424us : blk_flush_plug_list <-io_schedule_timeout [ 249.148009] s2disk-3327 2.... 48550425us : schedule_timeout <-io_schedule_timeout [ 249.148009] s2disk-3327 2.... 48550425us : lock_timer_base.isra.35 <-__mod_timer [ 249.148009] s2disk-3327 2.... 48550425us : _raw_spin_lock_irqsave <-lock_timer_base.isra.35 [ 249.148009] s2disk-3327 2d... 48550425us : detach_if_pending <-__mod_timer [ 249.148009] s2disk-3327 2d... 48550425us : idle_cpu <-__mod_timer [ 249.148009] s2disk-3327 2d... 48550425us : internal_add_timer <-__mod_timer [ 249.148009] s2disk-3327 2d... 48550425us : __internal_add_timer <-internal_add_timer [ 249.148009] s2disk-3327 2d... 48550426us : _raw_spin_unlock_irqrestore <-__mod_timer [ 249.148009] s2disk-3327 2.... 48550426us : schedule <-schedule_timeout [ 249.148009] s2disk-3327 2.... 48550426us : __schedule <-schedule_timeout [ 249.148009] s2disk-3327 2.... 48550426us : rcu_note_context_switch <-__schedule [ 249.148009] s2disk-3327 2.... 48550426us : rcu_sched_qs <-rcu_note_context_switch [ 249.148009] s2disk-3327 2.... 48550426us : _raw_spin_lock_irq <-__schedule [ 249.148009] s2disk-3327 2d... 48550427us : deactivate_task <-__schedule [ 249.148009] s2disk-3327 2d... 48550427us : dequeue_task <-__schedule [ 249.148009] s2disk-3327 2d... 48550427us : update_rq_clock <-dequeue_task [ 249.148009] s2disk-3327 2d... 48550427us : dequeue_task_fair <-__schedule [ 249.148009] s2disk-3327 2d... 48550427us : update_curr <-dequeue_task_fair [ 249.148009] s2disk-3327 2d... 48550427us : update_min_vruntime <-update_curr [ 249.148009] s2disk-3327 2d... 48550427us : cpuacct_charge <-update_curr [ 249.148009] s2disk-3327 2d... 48550428us : update_cfs_rq_blocked_load <-dequeue_task_fair [ 249.148009] s2disk-3327 2d... 48550428us : clear_buddies <-dequeue_task_fair [ 249.148009] s2disk-3327 2d... 48550428us : account_entity_dequeue <-dequeue_task_fair [ 249.148009] s2disk-3327 2d... 48550428us : update_min_vruntime <-dequeue_task_fair [ 249.148009] s2disk-3327 2d... 48550428us : update_cfs_shares <-dequeue_task_fair [ 249.148009] s2disk-3327 2d... 48550428us : update_curr <-update_cfs_shares [ 249.148009] s2disk-3327 2d... 48550429us : update_min_vruntime <-update_curr [ 249.148009] s2disk-3327 2d... 48550429us : account_entity_dequeue <-update_cfs_shares [ 249.148009] s2disk-3327 2d... 48550429us : account_entity_enqueue <-dequeue_task_fair [ 249.148009] s2disk-3327 2d... 48550429us : update_curr <-dequeue_task_fair [ 249.148009] s2disk-3327 2d... 48550429us : update_cfs_rq_blocked_load <-dequeue_task_fair [ 249.148009] s2disk-3327 2d... 48550429us : clear_buddies <-dequeue_task_fair [ 249.148009] s2disk-3327 2d... 48550429us : account_entity_dequeue <-dequeue_task_fair [ 249.148009] s2disk-3327 2d... 48550430us : update_min_vruntime <-dequeue_task_fair [ 249.148009] s2disk-3327 2d... 48550430us : update_cfs_shares <-dequeue_task_fair [ 249.148009] s2disk-3327 2d... 48550430us : hrtick_update <-__schedule [ 249.148009] s2disk-3327 2d... 48550430us : put_prev_task_fair <-__schedule [ 249.148009] s2disk-3327 2d... 48550430us : pick_next_task_fair <-pick_next_task [ 249.148009] s2disk-3327 2d... 48550430us : clear_buddies <-pick_next_task_fair [ 249.148009] s2disk-3327 2d... 48550431us : __dequeue_entity <-pick_next_task_fair but the worker wakeup doesn't actually do anything: [ 249.148009] kworker/-3466 2d... 48550431us : finish_task_switch <-__schedule [ 249.148009] kworker/-3466 2.... 48550431us : _raw_spin_lock_irq <-worker_thread [ 249.148009] kworker/-3466 2d... 48550431us : need_to_create_worker <-worker_thread [ 249.148009] kworker/-3466 2d... 48550432us : worker_enter_idle <-worker_thread [ 249.148009] kworker/-3466 2d... 48550432us : too_many_workers <-worker_enter_idle [ 249.148009] kworker/-3466 2.... 48550432us : schedule <-worker_thread [ 249.148009] kworker/-3466 2.... 48550432us : __schedule <-worker_thread My suspicion is that this fails because the bdi_wq is frozen at this point and so the flush work never runs until resume, whereas before my patch the effective dirty limit was high enough so that image could be written in one go without being throttled; followed by an fsync() that then writes the pages in the context of the unfrozen s2disk. Does this make sense? Rafael? Tejun? > 2) /sys/kernel/debug/bdi/<dev>/stats > > They are also in [1] - however the major/minors of my sdbX didn't > match with the /sys/.../bdi/<dev>'s. So I just displayed them all. > > 3) What is the estimated bandwith? > > It's an Samsung SSD 840 PRO, in this system: Read: 237 MB/s, Write 265 > MB/s - see [2] (the faster writing is maybe due caching?) > > > Just by curiosity: > > Can you also reproduce it ? ... since the test is quite simple. > Or is it something specific in my system here ? I tried to reproduce it here but could never get to hang it in balance_dirty_pages() like you did. Thanks, Johannes > [1] Attached session.log.s2disk.20140505_2238.bz2 > - 18MiB uncompressed function-trace output + others > - The bdi outputs are also in there > > [2] Rough bandwidth tests > Read: > --- > gamix64:~# swapon -s > Filename Type Size Used Priority > /dev/sdb7 partition 4193276 0 -1 > gamix64:~# dd if=/dev/sdb7 bs=1024 count=$[1024*1024*4] |pv >/dev/null > 4GB 0:00:18 [ 226MB/s] [ <=> ]4193280+0 records in > 4193280+0 records out > > 4293918720 bytes (4.3 GB) copied, 18.1509 s, 237 MB/s > --- > > Write: > --- > gamix64:~# dd if=/dev/zero bs=1024 count=$[1024*1024*4] |pv >/root/Test/test1.bin > 4194304+0 records inMB/s] [ <=> ] > 4194304+0 records out > 4294967296 bytes (4.3 GB) copied, 16.2039 s, 265 MB/s > 4GB 0:00:15 [ 256MB/s] [ <=> ] > --- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>