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Faster checksum benchmark on system boot #17945
Description
System information
| Type | Version/Name |
|---|---|
| Distribution Name | Gentoo |
| Distribution Version | |
| Kernel Version | 6.12.41 |
| Architecture | x86_64 |
| OpenZFS Version | 2.2.8 + #17563, 2.3.4, 2.4.0_rc2 |
Describe the problem you're observing
During testing the patches for 2.2.9, the following behavior was observed on Gentoo after applying #17563.
implementation 1k 4k 16k 64k 256k 1m 4m 16m
edonr-generic 749 840 977 1628 0 1573 1558 1446
skein-generic 516 563 595 595 0 546 604 481
sha256-generic 101 107 111 110 0 110 111 110
sha256-x64 255 288 178 207 0 225 298 299
sha256-ssse3 328 366 376 373 0 377 377 366
sha512-generic 290 326 337 334 0 334 310 334
sha512-x64 400 452 462 478 0 475 465 463
blake3-generic 345 382 367 377 0 370 373 370
blake3-sse2 424 1242 1315 1415 0 1391 1337 1356
blake3-sse41 480 1444 1636 1676 0 1608 1549 1610
The issue also occurs on the 2.3 and 2.4 branches, which already include this patch.
Describe how to reproduce the problem
cat /proc/spl/kstat/zfs/chksum_bench
Is it reproducible on your systems?
Activity
chksum: run 256K benchmark on demand
chksum: run 256K benchmark on demand
chksum: run 256K benchmark on demand
lundman commentedon Nov 17, 2025
oo, ooh i can suggest this again!
#17563 (comment)
behlendorf commentedon Nov 18, 2025
Sorry, but it's not clear to me. Do we end up selecting the wrong implementation here, or is it mainly a cosmetic issue?
lzsaver commentedon Nov 18, 2025
Sorry that there are no ready answers right now, because it is unclear why zeros are being shown.
It can be assumed that @mcmilk will log in in about five hours and will clear things up.
P.S. Something ate the "Signed‑off‑by" line in the quick‑fix PR. This will be fixed.
mcmilk commentedon Nov 18, 2025
It's a cosmetic issue. I wanted to re-use the 256k benchmark value.
mcmilk commentedon Nov 18, 2025
Yes, this makes sense.
I have two questions for implementation:
zfs_sha512_impl=avx- or should only thesha512tests be skipped then.cat /proc/spl/kstat/zfs/chksum_benchalways benchmark all possible algorithms?chksum: run 256K benchmark on demand
lzsaver commentedon Nov 21, 2025
Yes, otherwise there is no way to display the real results obtained with the current governor.
However, we need to make sure that we always have enough memory to run the benchmark.
Update:
If something is to be skipped, how can users change their choice if they have incomplete information.
Currently, any user can make requests, which poses a risk of a DoS attack, which must be prevented.
zfs_chksum: preserve chksum_stat_data between runs
zfs_chksum: preserve chksum_stat_data between runs
zfs_chksum: preserve chksum_stat_data between runs
zfs_chksum: preserve chksum_stat_data between runs
zfs_chksum: preserve chksum_stat_data between runs
zfs_chksum: run 256K benchmark on demand
chksum: run all benchmarks on demand
chksum: run 256K benchmark on demand, preserve chksum_stat_data
chksum: run 256K benchmark on demand, preserve chksum_stat_data
lzsaver commentedon Nov 26, 2025
AT_STARTUP benchmarks can be skipped if they are not needed, but all AT_BENCHMARK ones should be done.
chksum: run 256K benchmark on demand, preserve chksum_stat_data
chksum: run 256K benchmark on demand, preserve chksum_stat_data
chksum: run 256K benchmark on demand, preserve chksum_stat_data
chksum: run 256K benchmark on demand, preserve chksum_stat_data
chksum: run 256K benchmark on demand, preserve chksum_stat_data
chksum: run 256K benchmark on demand, preserve chksum_stat_data
chksum: run 256K benchmark on demand, preserve chksum_stat_data
chksum: run 256K benchmark on demand, preserve chksum_stat_data