ZFS:arc_prune 使用 100% CPU,且平均负载较高

ZFS:arc_prune 使用 100% CPU,且平均负载较高

我有一个4磁盘存储服务器两个 ZFS raidz1 池昨晚突然开始运行100% CPU高平均负载

root@stg1:~# w
 07:05:48 up 296 days, 17:19,  1 user,  load average: 27.06, 25.49, 24.74
USER     TTY      FROM             LOGIN@   IDLE   JCPU   PCPU WHAT

我有许多 arc_prune 进程,它们消耗了大量的 CPU:

arc_prune 使用大量 CPU

我的zfs_arc_max大小是默认大小(应该是系统 RAM 的 50%),实际上它使用的内存不超过 16 Gb:

------------------------------------------------------------------------
ZFS Subsystem Report                Thu Aug 27 07:09:34 2020
ARC Summary: (HEALTHY)
    Memory Throttle Count:          0

ARC Misc:
    Deleted:                567.62m
    Mutex Misses:               10.46m
    Evict Skips:                10.46m

ARC Size:               102.63% 15.99   GiB
    Target Size: (Adaptive)     100.00% 15.58   GiB
    Min Size (Hard Limit):      6.25%   996.88  MiB
    Max Size (High Water):      16:1    15.58   GiB

ARC Size Breakdown:
    Recently Used Cache Size:   56.67%  9.06    GiB
    Frequently Used Cache Size: 43.33%  6.93    GiB

ARC Hash Breakdown:
    Elements Max:               1.48m
    Elements Current:       21.99%  325.26k
    Collisions:             62.96m
    Chain Max:              6
    Chains:                 12.66k

ARC Total accesses:                 36.36b
    Cache Hit Ratio:        81.78%  29.74b
    Cache Miss Ratio:       18.22%  6.62b
    Actual Hit Ratio:       81.55%  29.65b

    Data Demand Efficiency:     89.52%  598.92m
    Data Prefetch Efficiency:   22.19%  7.58m

    CACHE HITS BY CACHE LIST:
      Anonymously Used:     0.18%   53.22m
      Most Recently Used:       2.05%   608.89m
      Most Frequently Used:     97.66%  29.04b
      Most Recently Used Ghost: 0.05%   14.79m
      Most Frequently Used Ghost:   0.06%   17.72m

    CACHE HITS BY DATA TYPE:
      Demand Data:          1.80%   536.16m
      Prefetch Data:        0.01%   1.68m
      Demand Metadata:      97.83%  29.09b
      Prefetch Metadata:        0.36%   107.49m

    CACHE MISSES BY DATA TYPE:
      Demand Data:          0.95%   62.77m
      Prefetch Data:        0.09%   5.89m
      Demand Metadata:      97.10%  6.43b
      Prefetch Metadata:        1.87%   123.70m


DMU Prefetch Efficiency:                    12.04b
    Hit Ratio:          1.04%   124.91m
    Miss Ratio:         98.96%  11.92b



ZFS Tunable:
    zfs_arc_p_min_shift                               0
    zfs_checksums_per_second                          20
    zvol_request_sync                                 0
    zfs_object_mutex_size                             64
    spa_slop_shift                                    5
    zfs_sync_taskq_batch_pct                          75
    zfs_vdev_async_write_max_active                   10
    zfs_multilist_num_sublists                        0
    zfs_no_scrub_prefetch                             0
    zfs_vdev_sync_read_min_active                     10
    zfs_dmu_offset_next_sync                          0
    metaslab_debug_load                               0
    zfs_vdev_mirror_rotating_seek_inc                 5
    zfs_vdev_mirror_non_rotating_inc                  0
    zfs_read_history                                  0
    zfs_multihost_history                             0
    zfs_metaslab_switch_threshold                     2
    metaslab_fragmentation_factor_enabled             1
    zfs_admin_snapshot                                1
    zfs_delete_blocks                                 20480
    zfs_arc_meta_prune                                10000
    zfs_free_min_time_ms                              1000
    zfs_dedup_prefetch                                0
    zfs_txg_history                                   0
    zfs_vdev_max_active                               1000
    zfs_vdev_sync_write_min_active                    10
    spa_load_verify_data                              1
    zfs_dirty_data_max_max                            4294967296
    zfs_send_corrupt_data                             0
    zfs_scan_min_time_ms                              1000
    dbuf_cache_lowater_pct                            10
    zfs_send_queue_length                             16777216
    dmu_object_alloc_chunk_shift                      7
    zfs_arc_shrink_shift                              0
    zfs_resilver_min_time_ms                          3000
    zfs_free_bpobj_enabled                            1
    zfs_vdev_mirror_non_rotating_seek_inc             1
    zfs_vdev_cache_max                                16384
    ignore_hole_birth                                 1
    zfs_multihost_fail_intervals                      5
    zfs_arc_sys_free                                  0
    zfs_sync_pass_dont_compress                       5
    zio_taskq_batch_pct                               75
    zfs_arc_meta_limit_percent                        75
    zfs_arc_p_dampener_disable                        1
    spa_load_verify_metadata                          1
    dbuf_cache_hiwater_pct                            10
    zfs_read_chunk_size                               1048576
    zfs_arc_grow_retry                                0
    metaslab_aliquot                                  524288
    zfs_vdev_async_read_min_active                    1
    zfs_vdev_cache_bshift                             16
    metaslab_preload_enabled                          1
    l2arc_feed_min_ms                                 200
    zfs_scrub_delay                                   4
    zfs_read_history_hits                             0
    zfetch_max_distance                               8388608
    send_holes_without_birth_time                     1
    zfs_max_recordsize                                1048576
    zfs_dbuf_state_index                              0
    dbuf_cache_max_bytes                              104857600
    zfs_zevent_cols                                   80
    zfs_no_scrub_io                                   0
    zil_slog_bulk                                     786432
    spa_asize_inflation                               24
    l2arc_write_boost                                 8388608
    zfs_arc_meta_limit                                0
    zfs_deadman_enabled                               1
    zfs_abd_scatter_enabled                           1
    zfs_vdev_async_write_active_min_dirty_percent     30
    zfs_free_leak_on_eio                              0
    zfs_vdev_cache_size                               0
    zfs_vdev_write_gap_limit                          4096
    l2arc_headroom                                    2
    zfs_per_txg_dirty_frees_percent                   30
    zfs_compressed_arc_enabled                        1
    zfs_scan_ignore_errors                            0
    zfs_resilver_delay                                2
    zfs_metaslab_segment_weight_enabled               1
    zfs_dirty_data_max_max_percent                    25
    zio_dva_throttle_enabled                          1
    zfs_vdev_scrub_min_active                         1
    zfs_arc_average_blocksize                         8192
    zfs_vdev_queue_depth_pct                          1000
    zfs_multihost_interval                            1000
    zio_requeue_io_start_cut_in_line                  1
    spa_load_verify_maxinflight                       10000
    zfetch_max_streams                                8
    zfs_multihost_import_intervals                    10
    zfs_mdcomp_disable                                0
    zfs_zevent_console                                0
    zfs_sync_pass_deferred_free                       2
    zfs_nocacheflush                                  0
    zfs_arc_dnode_limit                               0
    zfs_delays_per_second                             20
    zfs_dbgmsg_enable                                 0
    zfs_scan_idle                                     50
    zfs_vdev_raidz_impl                               [fastest] original scalar
    zio_delay_max                                     30000
    zvol_threads                                      32
    zfs_vdev_async_write_min_active                   2
    zfs_vdev_sync_read_max_active                     10
    l2arc_headroom_boost                              200
    zfs_sync_pass_rewrite                             2
    spa_config_path                                   /etc/zfs/zpool.cache
    zfs_pd_bytes_max                                  52428800
    zfs_dirty_data_sync                               67108864
    zfs_flags                                         0
    zfs_deadman_checktime_ms                          5000
    zfs_dirty_data_max_percent                        10
    zfetch_min_sec_reap                               2
    zfs_mg_noalloc_threshold                          0
    zfs_arc_meta_min                                  0
    zvol_prefetch_bytes                               131072
    zfs_deadman_synctime_ms                           1000000
    zfs_autoimport_disable                            1
    zfs_arc_min                                       0
    l2arc_noprefetch                                  1
    zfs_nopwrite_enabled                              1
    l2arc_feed_again                                  1
    zfs_vdev_sync_write_max_active                    10
    zfs_prefetch_disable                              0
    zfetch_array_rd_sz                                1048576
    zfs_metaslab_fragmentation_threshold              70
    l2arc_write_max                                   8388608
    zfs_dbgmsg_maxsize                                4194304
    zfs_vdev_read_gap_limit                           32768
    zfs_delay_min_dirty_percent                       60
    zfs_recv_queue_length                             16777216
    zfs_vdev_async_write_active_max_dirty_percent     60
    metaslabs_per_vdev                                200
    zfs_arc_lotsfree_percent                          10
    zfs_immediate_write_sz                            32768
    zil_replay_disable                                0
    zfs_vdev_mirror_rotating_inc                      0
    zvol_volmode                                      1
    zfs_arc_meta_strategy                             1
    dbuf_cache_max_shift                              5
    metaslab_bias_enabled                             1
    zfs_vdev_async_read_max_active                    3
    l2arc_feed_secs                                   1
    zfs_arc_max                                       0
    zfs_zevent_len_max                                256
    zfs_free_max_blocks                               100000
    zfs_top_maxinflight                               32
    zfs_arc_meta_adjust_restarts                      4096
    l2arc_norw                                        0
    zfs_recover                                       0
    zvol_inhibit_dev                                  0
    zfs_vdev_aggregation_limit                        131072
    zvol_major                                        230
    metaslab_debug_unload                             0
    metaslab_lba_weighting_enabled                    1
    zfs_txg_timeout                                   5
    zfs_arc_min_prefetch_lifespan                     0
    zfs_vdev_scrub_max_active                         2
    zfs_vdev_mirror_rotating_seek_offset              1048576
    zfs_arc_pc_percent                                0
    zfs_vdev_scheduler                                noop
    zvol_max_discard_blocks                           16384
    zfs_arc_dnode_reduce_percent                      10
    zfs_dirty_data_max                                3344961536
    zfs_abd_scatter_max_order                         10
    zfs_expire_snapshot                               300
    zfs_arc_dnode_limit_percent                       10
    zfs_delay_scale                                   500000
    zfs_mg_fragmentation_threshold                    85

这些是我的 ZFS 池:

root@stg1:~# zpool status
  pool: bpool
 state: ONLINE
status: Some supported features are not enabled on the pool. The pool can
    still be used, but some features are unavailable.
action: Enable all features using 'zpool upgrade'. Once this is done,
    the pool may no longer be accessible by software that does not support
    the features. See zpool-features(5) for details.
  scan: scrub repaired 0B in 0h0m with 0 errors on Sun Aug  9 00:24:06 2020
config:

    NAME                                         STATE     READ WRITE CKSUM
    bpool                                        ONLINE       0     0     0
      raidz1-0                                   ONLINE       0     0     0
        ata-HGST_HUH721010ALE600_JEJRYJ7N-part3  ONLINE       0     0     0
        ata-HGST_HUH721010ALE600_JEKELZTZ-part3  ONLINE       0     0     0
        ata-HGST_HUH721010ALE600_JEKEW7PZ-part3  ONLINE       0     0     0
        ata-HGST_HUH721010ALE600_JEKG492Z-part3  ONLINE       0     0     0

errors: No known data errors

  pool: rpool
 state: ONLINE
  scan: scrub repaired 0B in 7h34m with 0 errors on Sun Aug  9 07:58:40 2020
config:

    NAME                                         STATE     READ WRITE CKSUM
    rpool                                        ONLINE       0     0     0
      raidz1-0                                   ONLINE       0     0     0
        ata-HGST_HUH721010ALE600_JEJRYJ7N-part4  ONLINE       0     0     0
        ata-HGST_HUH721010ALE600_JEKELZTZ-part4  ONLINE       0     0     0
        ata-HGST_HUH721010ALE600_JEKEW7PZ-part4  ONLINE       0     0     0
        ata-HGST_HUH721010ALE600_JEKG492Z-part4  ONLINE       0     0     0

errors: No known data errors

驱动器为 SATA,不幸的是我无法添加任何缓存 SSD 设备。

我可以做些什么来释放一些 CPU?

答案1

某些因素正在迫使 ZFS 通过缩小 ARC 来回收内存。要立即解决此问题,您可以尝试发出

echo 1 > /proc/sys/vm/drop_caches仅删除 Linux 页面缓存,或者

echo 3 > /proc/sys/vm/drop_caches删除 Linux 页面缓存

但是,为了再次避免这种情况,您应该确定导致内存压力的原因,并在必要时进行zfs_arc_min相同的设置zfs_arc_max(基本上禁用 ARC 修剪)。

编辑:根据您的free输出,您的问题似乎与页面缓存无关。相反,您当前的 ARC 大小是,导致 shrinker 线程被唤醒。但是zfs_arc_max,它们似乎无法释放任何内存。我建议写信给 zfs 邮件列表[email protected]寻求进一步帮助。如果您需要立即解决问题,请发出上面描述的第二个命令 ( echo 3 > /proc/sys/vm/drop_caches)

相关内容