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Trim needless zeroes from checksum events #14716

Merged
merged 1 commit into from
Apr 10, 2023
Merged

Trim needless zeroes from checksum events #14716

merged 1 commit into from
Apr 10, 2023

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asomers
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@asomers asomers commented Apr 4, 2023

The ereport.fs.zfs.checksum event contains histograms of the bits that were wrongly set or cleared according to their bit position in a 64-bit word. So the maximum value that any histogram bucket could have would be 64. But ZFS currently uses a uint32_t to hold each bucket. As a result, the event report is full of needless zeroes.

Change the bucket size to uint8_t, stripping 768 needless zeros from each event.

Original event format:

 class=ereport.fs.zfs.checksum ena=639460469834258433 pool=testpool.1933 pool_guid=4979719877084416563 pool_state=0 pool_context=0 pool_failmode=wait vdev_guid=4136721804819128578 vdev_type=file vdev_path=/tmp/kyua.1TxP3A/2/work/file1.1933 vdev_ashift=9 vdev_complete_ts=609837019678 vdev_delta_ts=33450 vdev_read_errors=0 vdev_write_errors=0 vdev_cksum_errors=20 vdev_delays=0 parent_guid=2751977006639883417 parent_type=raidz vdev_spare_guids= zio_err=0 zio_flags=1048752 zio_stage=4194304 zio_pipeline=65011712 zio_delay=0 zio_timestamp=0 zio_delta=0 zio_priority=4 zio_offset=702976 zio_size=1024 zio_objset=24 zio_object=0 zio_level=3 zio_blkid=0 bad_ranges=0000000000000400 bad_ranges_min_gap=8 bad_range_sets=0000079e bad_range_clears=00000854 bad_set_histogram=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 bad_cleared_histogram=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 time=00000016806457270000000323406839 eid=458

New format:

 class=ereport.fs.zfs.checksum ena=96599319807790081 pool=testpool.1933 pool_guid=1236902063710799041 pool_state=0 pool_context=0 pool_failmode=wait vdev_guid=2774253874431514999 vdev_type=file vdev_path=/tmp/kyua.6Temlq/2/work/file1.1933 vdev_ashift=9 vdev_complete_ts=92124283803 vdev_delta_ts=46670 vdev_read_errors=0 vdev_write_errors=0 vdev_cksum_errors=20 vdev_delays=0 parent_guid=8090931855087882905 parent_type=raidz vdev_spare_guids= zio_err=0 zio_flags=1048752 zio_stage=4194304 zio_pipeline=65011712 zio_delay=0 zio_timestamp=0 zio_delta=0 zio_priority=4 zio_offset=1028608 zio_size=512 zio_objset=0 zio_object=0 zio_level=0 zio_blkid=4 bad_ranges=0000000000000200 bad_ranges_min_gap=8 bad_range_sets=0000061f bad_range_clears=000001f4 bad_set_histogram=1719161c1c1c101618171a151a1a19161e1c171d1816161c191f1a18192117191c131d171b1613151a171419161a1b1319101b14171b18151e191a1b141a1c17 bad_cleared_histogram=06090a0808070a0b020609060506090a01090a050a0a0509070609080d050d0607080d060507080c04070807070a0608020c080c080908040808090a05090a07 time=00000016806477050000000604157480 eid=62

Sponsored-by: Axcient
Signed-off-by: Alan Somers asomers@FreeBSD.org

Motivation and Context

On FreeBSD, devctl events must fit within a 1016 byte buffer or they will not be reported to userland. Checksum events are far too big, as of FreeBSD 14.0-CURRENT. As a result, userland processes will never receive the event.

This PR reduces the event size by 768, which is almost but not quite enough. It should however be uncontroversial. In order to completely fix the problem we will probably need to strip other fields from the event, and that will require some debate.

Description

Report the histograms to userland as arrays of 8-bit values instead of 32-bit values. This means the final event won't contain any redundant zeros. That is, 000000210000001a000000150000001d... will become 211a151d....

How Has This Been Tested?

Tested by running the zfsd_degrade_001_pos test on FreeBSD 14.0-CURRENT while watching events arriving in both devd's log and with dtrace.

Types of changes

  • Bug fix (non-breaking change which fixes an issue)
  • New feature (non-breaking change which adds functionality)
  • Performance enhancement (non-breaking change which improves efficiency)
  • Code cleanup (non-breaking change which makes code smaller or more readable)
  • Breaking change (fix or feature that would cause existing functionality to change)
  • Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
  • Documentation (a change to man pages or other documentation)

Checklist:

@asomers
Trim needless zeroes from checksum events
80dfb38 
The ereport.fs.zfs.checksum event contains histograms of the bits that
were wrongly set or cleared according to their bit position in a 64-bit
word.  So the maximum value that any histogram bucket could have would
be 64.  But ZFS currently uses a uint32_t to hold each bucket.  As a
result, the event report is full of needless zeroes.

Change the bucket size to uint8_t, stripping 768 needless zeros from
each event.

Original event format:
```
 class=ereport.fs.zfs.checksum ena=639460469834258433 pool=testpool.1933 pool_guid=4979719877084416563 pool_state=0 pool_context=0 pool_failmode=wait vdev_guid=4136721804819128578 vdev_type=file vdev_path=/tmp/kyua.1TxP3A/2/work/file1.1933 vdev_ashift=9 vdev_complete_ts=609837019678 vdev_delta_ts=33450 vdev_read_errors=0 vdev_write_errors=0 vdev_cksum_errors=20 vdev_delays=0 parent_guid=2751977006639883417 parent_type=raidz vdev_spare_guids= zio_err=0 zio_flags=1048752 zio_stage=4194304 zio_pipeline=65011712 zio_delay=0 zio_timestamp=0 zio_delta=0 zio_priority=4 zio_offset=702976 zio_size=1024 zio_objset=24 zio_object=0 zio_level=3 zio_blkid=0 bad_ranges=0000000000000400 bad_ranges_min_gap=8 bad_range_sets=0000079e bad_range_clears=00000854 bad_set_histogram=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 bad_cleared_histogram=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 time=00000016806457270000000323406839 eid=458
```

New format:
```
 class=ereport.fs.zfs.checksum ena=96599319807790081 pool=testpool.1933 pool_guid=1236902063710799041 pool_state=0 pool_context=0 pool_failmode=wait vdev_guid=2774253874431514999 vdev_type=file vdev_path=/tmp/kyua.6Temlq/2/work/file1.1933 vdev_ashift=9 vdev_complete_ts=92124283803 vdev_delta_ts=46670 vdev_read_errors=0 vdev_write_errors=0 vdev_cksum_errors=20 vdev_delays=0 parent_guid=8090931855087882905 parent_type=raidz vdev_spare_guids= zio_err=0 zio_flags=1048752 zio_stage=4194304 zio_pipeline=65011712 zio_delay=0 zio_timestamp=0 zio_delta=0 zio_priority=4 zio_offset=1028608 zio_size=512 zio_objset=0 zio_object=0 zio_level=0 zio_blkid=4 bad_ranges=0000000000000200 bad_ranges_min_gap=8 bad_range_sets=0000061f bad_range_clears=000001f4 bad_set_histogram=1719161c1c1c101618171a151a1a19161e1c171d1816161c191f1a18192117191c131d171b1613151a171419161a1b1319101b14171b18151e191a1b141a1c17 bad_cleared_histogram=06090a0808070a0b020609060506090a01090a050a0a0509070609080d050d0607080d060507080c04070807070a0608020c080c080908040808090a05090a07 time=00000016806477050000000604157480 eid=62
```

Sponsored-by:  Axcient
Signed-off-by:  Alan Somers <asomers@FreeBSD.org>
@asomers asomers mentioned this pull request Apr 4, 2023
Closed
@asomers
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asomers commented Apr 4, 2023

The checkstyle failure is because my commit message contains lines over 72 characters, which is kind of the whole point for this PR. Can we ignore the checkstyle failure please?

@behlendorf behlendorf added the Status: Code Review Needed Ready for review and testing label Apr 6, 2023
@behlendorf behlendorf added Status: Accepted Ready to integrate (reviewed, tested) and removed Status: Code Review Needed Ready for review and testing labels Apr 10, 2023
@behlendorf behlendorf merged commit 678a3b8 into openzfs:master Apr 10, 2023
andrewc12 pushed a commit to andrewc12/openzfs that referenced this pull request Apr 11, 2023
@asomers @andrewc12
Trim needless zeroes from checksum events
5f5dbdb 
The ereport.fs.zfs.checksum event contains histograms of the bits that
were wrongly set or cleared according to their bit position in a 64-bit
word.  So the maximum value that any histogram bucket could have would
be 64.  But ZFS currently uses a uint32_t to hold each bucket.  As a
result, the event report is full of needless zeroes.

Change the bucket size to uint8_t, stripping 768 needless zeros from
each event.

Original event format:
```
 class=ereport.fs.zfs.checksum ena=639460469834258433 pool=testpool.1933 pool_guid=4979719877084416563 pool_state=0 pool_context=0 pool_failmode=wait vdev_guid=4136721804819128578 vdev_type=file vdev_path=/tmp/kyua.1TxP3A/2/work/file1.1933 vdev_ashift=9 vdev_complete_ts=609837019678 vdev_delta_ts=33450 vdev_read_errors=0 vdev_write_errors=0 vdev_cksum_errors=20 vdev_delays=0 parent_guid=2751977006639883417 parent_type=raidz vdev_spare_guids= zio_err=0 zio_flags=1048752 zio_stage=4194304 zio_pipeline=65011712 zio_delay=0 zio_timestamp=0 zio_delta=0 zio_priority=4 zio_offset=702976 zio_size=1024 zio_objset=24 zio_object=0 zio_level=3 zio_blkid=0 bad_ranges=0000000000000400 bad_ranges_min_gap=8 bad_range_sets=0000079e bad_range_clears=00000854 bad_set_histogram=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 bad_cleared_histogram=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 time=00000016806457270000000323406839 eid=458
```

New format:
```
 class=ereport.fs.zfs.checksum ena=96599319807790081 pool=testpool.1933 pool_guid=1236902063710799041 pool_state=0 pool_context=0 pool_failmode=wait vdev_guid=2774253874431514999 vdev_type=file vdev_path=/tmp/kyua.6Temlq/2/work/file1.1933 vdev_ashift=9 vdev_complete_ts=92124283803 vdev_delta_ts=46670 vdev_read_errors=0 vdev_write_errors=0 vdev_cksum_errors=20 vdev_delays=0 parent_guid=8090931855087882905 parent_type=raidz vdev_spare_guids= zio_err=0 zio_flags=1048752 zio_stage=4194304 zio_pipeline=65011712 zio_delay=0 zio_timestamp=0 zio_delta=0 zio_priority=4 zio_offset=1028608 zio_size=512 zio_objset=0 zio_object=0 zio_level=0 zio_blkid=4 bad_ranges=0000000000000200 bad_ranges_min_gap=8 bad_range_sets=0000061f bad_range_clears=000001f4 bad_set_histogram=1719161c1c1c101618171a151a1a19161e1c171d1816161c191f1a18192117191c131d171b1613151a171419161a1b1319101b14171b18151e191a1b141a1c17 bad_cleared_histogram=06090a0808070a0b020609060506090a01090a050a0a0509070609080d050d0607080d060507080c04070807070a0608020c080c080908040808090a05090a07 time=00000016806477050000000604157480 eid=62
```

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Signed-off-by: Alan Somers <asomers@FreeBSD.org>
Sponsored-by: Axcient
Closes openzfs#14716
andrewc12 pushed a commit to andrewc12/openzfs that referenced this pull request Apr 11, 2023
@asomers @andrewc12
Trim needless zeroes from checksum events
0888b71 
The ereport.fs.zfs.checksum event contains histograms of the bits that
were wrongly set or cleared according to their bit position in a 64-bit
word.  So the maximum value that any histogram bucket could have would
be 64.  But ZFS currently uses a uint32_t to hold each bucket.  As a
result, the event report is full of needless zeroes.

Change the bucket size to uint8_t, stripping 768 needless zeros from
each event.

Original event format:
```
 class=ereport.fs.zfs.checksum ena=639460469834258433 pool=testpool.1933 pool_guid=4979719877084416563 pool_state=0 pool_context=0 pool_failmode=wait vdev_guid=4136721804819128578 vdev_type=file vdev_path=/tmp/kyua.1TxP3A/2/work/file1.1933 vdev_ashift=9 vdev_complete_ts=609837019678 vdev_delta_ts=33450 vdev_read_errors=0 vdev_write_errors=0 vdev_cksum_errors=20 vdev_delays=0 parent_guid=2751977006639883417 parent_type=raidz vdev_spare_guids= zio_err=0 zio_flags=1048752 zio_stage=4194304 zio_pipeline=65011712 zio_delay=0 zio_timestamp=0 zio_delta=0 zio_priority=4 zio_offset=702976 zio_size=1024 zio_objset=24 zio_object=0 zio_level=3 zio_blkid=0 bad_ranges=0000000000000400 bad_ranges_min_gap=8 bad_range_sets=0000079e bad_range_clears=00000854 bad_set_histogram=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 bad_cleared_histogram=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 time=00000016806457270000000323406839 eid=458
```

New format:
```
 class=ereport.fs.zfs.checksum ena=96599319807790081 pool=testpool.1933 pool_guid=1236902063710799041 pool_state=0 pool_context=0 pool_failmode=wait vdev_guid=2774253874431514999 vdev_type=file vdev_path=/tmp/kyua.6Temlq/2/work/file1.1933 vdev_ashift=9 vdev_complete_ts=92124283803 vdev_delta_ts=46670 vdev_read_errors=0 vdev_write_errors=0 vdev_cksum_errors=20 vdev_delays=0 parent_guid=8090931855087882905 parent_type=raidz vdev_spare_guids= zio_err=0 zio_flags=1048752 zio_stage=4194304 zio_pipeline=65011712 zio_delay=0 zio_timestamp=0 zio_delta=0 zio_priority=4 zio_offset=1028608 zio_size=512 zio_objset=0 zio_object=0 zio_level=0 zio_blkid=4 bad_ranges=0000000000000200 bad_ranges_min_gap=8 bad_range_sets=0000061f bad_range_clears=000001f4 bad_set_histogram=1719161c1c1c101618171a151a1a19161e1c171d1816161c191f1a18192117191c131d171b1613151a171419161a1b1319101b14171b18151e191a1b141a1c17 bad_cleared_histogram=06090a0808070a0b020609060506090a01090a050a0a0509070609080d050d0607080d060507080c04070807070a0608020c080c080908040808090a05090a07 time=00000016806477050000000604157480 eid=62
```

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Signed-off-by: Alan Somers <asomers@FreeBSD.org>
Sponsored-by: Axcient
Closes openzfs#14716
andrewc12 pushed a commit to andrewc12/openzfs that referenced this pull request Apr 11, 2023
@asomers @andrewc12
Trim needless zeroes from checksum events
f1cf860 
The ereport.fs.zfs.checksum event contains histograms of the bits that
were wrongly set or cleared according to their bit position in a 64-bit
word.  So the maximum value that any histogram bucket could have would
be 64.  But ZFS currently uses a uint32_t to hold each bucket.  As a
result, the event report is full of needless zeroes.

Change the bucket size to uint8_t, stripping 768 needless zeros from
each event.

Original event format:
```
 class=ereport.fs.zfs.checksum ena=639460469834258433 pool=testpool.1933 pool_guid=4979719877084416563 pool_state=0 pool_context=0 pool_failmode=wait vdev_guid=4136721804819128578 vdev_type=file vdev_path=/tmp/kyua.1TxP3A/2/work/file1.1933 vdev_ashift=9 vdev_complete_ts=609837019678 vdev_delta_ts=33450 vdev_read_errors=0 vdev_write_errors=0 vdev_cksum_errors=20 vdev_delays=0 parent_guid=2751977006639883417 parent_type=raidz vdev_spare_guids= zio_err=0 zio_flags=1048752 zio_stage=4194304 zio_pipeline=65011712 zio_delay=0 zio_timestamp=0 zio_delta=0 zio_priority=4 zio_offset=702976 zio_size=1024 zio_objset=24 zio_object=0 zio_level=3 zio_blkid=0 bad_ranges=0000000000000400 bad_ranges_min_gap=8 bad_range_sets=0000079e bad_range_clears=00000854 bad_set_histogram=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 bad_cleared_histogram=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 time=00000016806457270000000323406839 eid=458
```

New format:
```
 class=ereport.fs.zfs.checksum ena=96599319807790081 pool=testpool.1933 pool_guid=1236902063710799041 pool_state=0 pool_context=0 pool_failmode=wait vdev_guid=2774253874431514999 vdev_type=file vdev_path=/tmp/kyua.6Temlq/2/work/file1.1933 vdev_ashift=9 vdev_complete_ts=92124283803 vdev_delta_ts=46670 vdev_read_errors=0 vdev_write_errors=0 vdev_cksum_errors=20 vdev_delays=0 parent_guid=8090931855087882905 parent_type=raidz vdev_spare_guids= zio_err=0 zio_flags=1048752 zio_stage=4194304 zio_pipeline=65011712 zio_delay=0 zio_timestamp=0 zio_delta=0 zio_priority=4 zio_offset=1028608 zio_size=512 zio_objset=0 zio_object=0 zio_level=0 zio_blkid=4 bad_ranges=0000000000000200 bad_ranges_min_gap=8 bad_range_sets=0000061f bad_range_clears=000001f4 bad_set_histogram=1719161c1c1c101618171a151a1a19161e1c171d1816161c191f1a18192117191c131d171b1613151a171419161a1b1319101b14171b18151e191a1b141a1c17 bad_cleared_histogram=06090a0808070a0b020609060506090a01090a050a0a0509070609080d050d0607080d060507080c04070807070a0608020c080c080908040808090a05090a07 time=00000016806477050000000604157480 eid=62
```

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Signed-off-by: Alan Somers <asomers@FreeBSD.org>
Sponsored-by: Axcient
Closes openzfs#14716
andrewc12 pushed a commit to andrewc12/openzfs that referenced this pull request Apr 12, 2023
@asomers @andrewc12
Trim needless zeroes from checksum events
8d83a40 
The ereport.fs.zfs.checksum event contains histograms of the bits that
were wrongly set or cleared according to their bit position in a 64-bit
word.  So the maximum value that any histogram bucket could have would
be 64.  But ZFS currently uses a uint32_t to hold each bucket.  As a
result, the event report is full of needless zeroes.

Change the bucket size to uint8_t, stripping 768 needless zeros from
each event.

Original event format:
```
 class=ereport.fs.zfs.checksum ena=639460469834258433 pool=testpool.1933 pool_guid=4979719877084416563 pool_state=0 pool_context=0 pool_failmode=wait vdev_guid=4136721804819128578 vdev_type=file vdev_path=/tmp/kyua.1TxP3A/2/work/file1.1933 vdev_ashift=9 vdev_complete_ts=609837019678 vdev_delta_ts=33450 vdev_read_errors=0 vdev_write_errors=0 vdev_cksum_errors=20 vdev_delays=0 parent_guid=2751977006639883417 parent_type=raidz vdev_spare_guids= zio_err=0 zio_flags=1048752 zio_stage=4194304 zio_pipeline=65011712 zio_delay=0 zio_timestamp=0 zio_delta=0 zio_priority=4 zio_offset=702976 zio_size=1024 zio_objset=24 zio_object=0 zio_level=3 zio_blkid=0 bad_ranges=0000000000000400 bad_ranges_min_gap=8 bad_range_sets=0000079e bad_range_clears=00000854 bad_set_histogram=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 bad_cleared_histogram=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 time=00000016806457270000000323406839 eid=458
```

New format:
```
 class=ereport.fs.zfs.checksum ena=96599319807790081 pool=testpool.1933 pool_guid=1236902063710799041 pool_state=0 pool_context=0 pool_failmode=wait vdev_guid=2774253874431514999 vdev_type=file vdev_path=/tmp/kyua.6Temlq/2/work/file1.1933 vdev_ashift=9 vdev_complete_ts=92124283803 vdev_delta_ts=46670 vdev_read_errors=0 vdev_write_errors=0 vdev_cksum_errors=20 vdev_delays=0 parent_guid=8090931855087882905 parent_type=raidz vdev_spare_guids= zio_err=0 zio_flags=1048752 zio_stage=4194304 zio_pipeline=65011712 zio_delay=0 zio_timestamp=0 zio_delta=0 zio_priority=4 zio_offset=1028608 zio_size=512 zio_objset=0 zio_object=0 zio_level=0 zio_blkid=4 bad_ranges=0000000000000200 bad_ranges_min_gap=8 bad_range_sets=0000061f bad_range_clears=000001f4 bad_set_histogram=1719161c1c1c101618171a151a1a19161e1c171d1816161c191f1a18192117191c131d171b1613151a171419161a1b1319101b14171b18151e191a1b141a1c17 bad_cleared_histogram=06090a0808070a0b020609060506090a01090a050a0a0509070609080d050d0607080d060507080c04070807070a0608020c080c080908040808090a05090a07 time=00000016806477050000000604157480 eid=62
```

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Signed-off-by: Alan Somers <asomers@FreeBSD.org>
Sponsored-by: Axcient
Closes openzfs#14716
andrewc12 pushed a commit to andrewc12/openzfs that referenced this pull request Apr 12, 2023
@asomers @andrewc12
Trim needless zeroes from checksum events
0873fb5 
The ereport.fs.zfs.checksum event contains histograms of the bits that
were wrongly set or cleared according to their bit position in a 64-bit
word.  So the maximum value that any histogram bucket could have would
be 64.  But ZFS currently uses a uint32_t to hold each bucket.  As a
result, the event report is full of needless zeroes.

Change the bucket size to uint8_t, stripping 768 needless zeros from
each event.

Original event format:
```
 class=ereport.fs.zfs.checksum ena=639460469834258433 pool=testpool.1933 pool_guid=4979719877084416563 pool_state=0 pool_context=0 pool_failmode=wait vdev_guid=4136721804819128578 vdev_type=file vdev_path=/tmp/kyua.1TxP3A/2/work/file1.1933 vdev_ashift=9 vdev_complete_ts=609837019678 vdev_delta_ts=33450 vdev_read_errors=0 vdev_write_errors=0 vdev_cksum_errors=20 vdev_delays=0 parent_guid=2751977006639883417 parent_type=raidz vdev_spare_guids= zio_err=0 zio_flags=1048752 zio_stage=4194304 zio_pipeline=65011712 zio_delay=0 zio_timestamp=0 zio_delta=0 zio_priority=4 zio_offset=702976 zio_size=1024 zio_objset=24 zio_object=0 zio_level=3 zio_blkid=0 bad_ranges=0000000000000400 bad_ranges_min_gap=8 bad_range_sets=0000079e bad_range_clears=00000854 bad_set_histogram=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 bad_cleared_histogram=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 time=00000016806457270000000323406839 eid=458
```

New format:
```
 class=ereport.fs.zfs.checksum ena=96599319807790081 pool=testpool.1933 pool_guid=1236902063710799041 pool_state=0 pool_context=0 pool_failmode=wait vdev_guid=2774253874431514999 vdev_type=file vdev_path=/tmp/kyua.6Temlq/2/work/file1.1933 vdev_ashift=9 vdev_complete_ts=92124283803 vdev_delta_ts=46670 vdev_read_errors=0 vdev_write_errors=0 vdev_cksum_errors=20 vdev_delays=0 parent_guid=8090931855087882905 parent_type=raidz vdev_spare_guids= zio_err=0 zio_flags=1048752 zio_stage=4194304 zio_pipeline=65011712 zio_delay=0 zio_timestamp=0 zio_delta=0 zio_priority=4 zio_offset=1028608 zio_size=512 zio_objset=0 zio_object=0 zio_level=0 zio_blkid=4 bad_ranges=0000000000000200 bad_ranges_min_gap=8 bad_range_sets=0000061f bad_range_clears=000001f4 bad_set_histogram=1719161c1c1c101618171a151a1a19161e1c171d1816161c191f1a18192117191c131d171b1613151a171419161a1b1319101b14171b18151e191a1b141a1c17 bad_cleared_histogram=06090a0808070a0b020609060506090a01090a050a0a0509070609080d050d0607080d060507080c04070807070a0608020c080c080908040808090a05090a07 time=00000016806477050000000604157480 eid=62
```

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Signed-off-by: Alan Somers <asomers@FreeBSD.org>
Sponsored-by: Axcient
Closes openzfs#14716
@asomers asomers deleted the ecksum_fewer_zeroes branch July 6, 2023 17:24
asomers added a commit to asomers/zfs that referenced this pull request Jul 10, 2023
@asomers
Fix the ZFS checksum error histograms with larger record sizes
1f661a3 
My analysis in PR openzfs#14716 was incorrect.  Each histogram bucket contains
the number of incorrect bits, by position in a 64-bit word, over the
entire record.  8-bit buckets can overflow for record sizes above 2k.
To forestall that, saturate each bucket at 255.  That should still get
the point across: either all bits are equally wrong, or just a couple
are.

Sponsored-by:	Axcient
Signed-off-by:	Alan Somers <asomers@gmail.com>
@asomers asomers mentioned this pull request Jul 10, 2023
Merged
13 tasks
behlendorf pushed a commit that referenced this pull request Jul 14, 2023
@asomers
Fix the ZFS checksum error histograms with larger record sizes
67c5e1b 
My analysis in PR #14716 was incorrect.  Each histogram bucket contains
the number of incorrect bits, by position in a 64-bit word, over the
entire record.  8-bit buckets can overflow for record sizes above 2k.
To forestall that, saturate each bucket at 255.  That should still get
the point across: either all bits are equally wrong, or just a couple
are.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alan Somers <asomers@gmail.com>
Sponsored-by: Axcient
Closes #15049
behlendorf pushed a commit to behlendorf/zfs that referenced this pull request Jul 21, 2023
@asomers @behlendorf
Fix the ZFS checksum error histograms with larger record sizes
4d73940 
My analysis in PR openzfs#14716 was incorrect.  Each histogram bucket contains
the number of incorrect bits, by position in a 64-bit word, over the
entire record.  8-bit buckets can overflow for record sizes above 2k.
To forestall that, saturate each bucket at 255.  That should still get
the point across: either all bits are equally wrong, or just a couple
are.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alan Somers <asomers@gmail.com>
Sponsored-by: Axcient
Closes openzfs#15049
behlendorf pushed a commit that referenced this pull request Jul 21, 2023
@asomers @behlendorf
Fix the ZFS checksum error histograms with larger record sizes
f917cf1 
My analysis in PR #14716 was incorrect.  Each histogram bucket contains
the number of incorrect bits, by position in a 64-bit word, over the
entire record.  8-bit buckets can overflow for record sizes above 2k.
To forestall that, saturate each bucket at 255.  That should still get
the point across: either all bits are equally wrong, or just a couple
are.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alan Somers <asomers@gmail.com>
Sponsored-by: Axcient
Closes #15049
lundman pushed a commit to openzfsonwindows/openzfs that referenced this pull request Dec 12, 2023
@asomers @lundman
Fix the ZFS checksum error histograms with larger record sizes
2580d29 
My analysis in PR openzfs#14716 was incorrect.  Each histogram bucket contains
the number of incorrect bits, by position in a 64-bit word, over the
entire record.  8-bit buckets can overflow for record sizes above 2k.
To forestall that, saturate each bucket at 255.  That should still get
the point across: either all bits are equally wrong, or just a couple
are.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alan Somers <asomers@gmail.com>
Sponsored-by: Axcient
Closes openzfs#15049
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