1. free
              total        used        free      shared  buff/cache
available
Mem:        8025436     1255616     6457736       11780      312084
6512296
Swap:       1425404           0     1425404

2. cat /proc/spl/kstat/zfs/arcstats
12 1 0x01 98 26656 4085867100 20862566338548
name                            type data
hits                            4    8977275
misses                          4    20770
demand_data_hits                4    7154775
demand_data_misses              4    13760
demand_metadata_hits            4    1810210
demand_metadata_misses          4    4292
prefetch_data_hits              4    112
prefetch_data_misses            4    719
prefetch_metadata_hits          4    12178
prefetch_metadata_misses        4    1999
mru_hits                        4    4041554
mru_ghost_hits                  4    0
mfu_hits                        4    4923504
mfu_ghost_hits                  4    0
deleted                         4    31
mutex_miss                      4    0
access_skip                     4    9
evict_skip                      4    124
evict_not_enough                4    0
evict_l2_cached                 4    0
evict_l2_eligible               4    396800
evict_l2_ineligible             4    8192
evict_l2_skip                   4    0
hash_elements                   4    20337
hash_elements_max               4    22033
hash_collisions                 4    82157
hash_chains                     4    196
hash_chain_max                  4    2
p                               4    2054511616
c                               4    4109023232
c_min                           4    256813952
c_max                           4    4109023232
size                            4    1856513648
compressed_size                 4    1349638144
uncompressed_size               4    1738882048
overhead_size                   4    446370304
hdr_size                        4    7828496
data_size                       4    1709473792
metadata_size                   4    86534656
dbuf_size                       4    9437376
dnode_size                      4    23086368
bonus_size                      4    20152960
anon_size                       4    438411264
anon_evictable_data             4    0
anon_evictable_metadata         4    0
mru_size                        4    1186710528
mru_evictable_data              4    908280320
mru_evictable_metadata          4    4658688
mru_ghost_size                  4    0
mru_ghost_evictable_data        4    0
mru_ghost_evictable_metadata    4    0
mfu_size                        4    170886656
mfu_evictable_data              4    134954496
mfu_evictable_metadata          4    3134976
mfu_ghost_size                  4    0
mfu_ghost_evictable_data        4    0
mfu_ghost_evictable_metadata    4    0
l2_hits                         4    0
l2_misses                       4    0
l2_feeds                        4    0
l2_rw_clash                     4    0
l2_read_bytes                   4    0
l2_write_bytes                  4    0
l2_writes_sent                  4    0
l2_writes_done                  4    0
l2_writes_error                 4    0
l2_writes_lock_retry            4    0
l2_evict_lock_retry             4    0
l2_evict_reading                4    0
l2_evict_l1cached               4    0
l2_free_on_write                4    0
l2_abort_lowmem                 4    0
l2_cksum_bad                    4    0
l2_io_error                     4    0
l2_size                         4    0
l2_asize                        4    0
l2_hdr_size                     4    0
memory_throttle_count           4    0
memory_direct_count             4    0
memory_indirect_count           4    0
memory_all_bytes                4    8218046464
memory_free_bytes               4    5230358528
memory_available_bytes          3    5101953024
arc_no_grow                     4    0
arc_tempreserve                 4    0
arc_loaned_bytes                4    0
arc_prune                       4    0
arc_meta_used                   4    147039856
arc_meta_limit                  4    3081767424
arc_dnode_limit                 4    308176742
arc_meta_max                    4    152895280
arc_meta_min                    4    16777216
async_upgrade_sync              4    59
demand_hit_predictive_prefetch  4    484
demand_hit_prescient_prefetch   4    0
arc_need_free                   4    0
arc_sys_free                    4    128406976
arc_raw_size                    4    0


This behavior was observed on more than one machine, both small and large
(the large was on AWS).

Thanks,
Andrey Gelman


On Mon, Jul 13, 2020 at 5:45 PM Colin Ian King <1883...@bugs.launchpad.net>
wrote:

> It would be interesting in knowing the following data:
>
> 1. How much memory does the machine have when booted?
>
> run: free
>
> 2. What the arcstats look like when it goes slowly
>
> use: cat /proc/spl/kstat/zfs/arcstats
>
> thanks
>
> ** Changed in: zfs-linux (Ubuntu)
>        Status: Confirmed => Incomplete
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1883676
>
> Title:
>   ZFS performance drops suddenly
>
> Status in zfs-linux package in Ubuntu:
>   Incomplete
>
> Bug description:
>   Run Phoronix Flexible IO / Random write benchmark.
>   After running the benchmark repeatedly multiple times (occasionally it
> can be 30 minutes or 8 hours), the performance drops suddenly. The only way
> (I know of) to get back to high performance is reboot.
>   ---
>       $ for i in $(seq 1 1000); do printf "2\n4\n2\n1\n1\n1\nn\n" |
> phoronix-test-suite run fio | awk '/Average.*IOPS/ {print $2}' >>
> /tmp/iops; done
>       $ less /tmp/iops
>       ...
>       2095
>       2095
>       2093
>       783
>       388
>       389
>       ...
>
>   ProblemType: Bug
>   DistroRelease: Ubuntu 18.04
>   Package: zfsutils-linux 0.7.5-1ubuntu16.9
>   ProcVersionSignature: User Name 5.3.0-1023.25~18.04.1-aws 5.3.18
>   Uname: Linux 5.3.0-1023-aws x86_64
>   NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
>   ApportVersion: 2.20.9-0ubuntu7.15
>   Architecture: amd64
>   Date: Tue Jun 16 08:55:01 2020
>   Ec2AMI: ami-06fd83ae47b05282f
>   Ec2AMIManifest: (unknown)
>   Ec2AvailabilityZone: us-east-1f
>   Ec2InstanceType: c4.xlarge
>   Ec2Kernel: unavailable
>   Ec2Ramdisk: unavailable
>   SourcePackage: zfs-linux
>   UpgradeStatus: No upgrade log present (probably fresh install)
>   modified.conffile..etc.sudoers.d.zfs: [deleted]
>
> To manage notifications about this bug go to:
>
> https://bugs.launchpad.net/ubuntu/+source/zfs-linux/+bug/1883676/+subscriptions
>

-- 
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/1883676

Title:
  ZFS performance drops suddenly

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/zfs-linux/+bug/1883676/+subscriptions

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