From Fedora Project Wiki
< Changes
No edit summary |
m (Change announced) |
||
| Line 92: | Line 92: | ||
* Proposal owners: submit a patch to redhat-rpm-config | * Proposal owners: submit a patch to redhat-rpm-config | ||
* Other developers: redhat-rpm-config maintainer: include the patch and make a new build | * Other developers: redhat-rpm-config maintainer: include the patch and make a new build | ||
* Release engineering: [https://pagure.io/releng/ | * Release engineering: [https://pagure.io/releng/issue/8395 #8395] mass rebuild is needed | ||
<!-- Does this feature require coordination with release engineering (e.g. changes to installer image generation or update package delivery)? Is a mass rebuild required? include a link to the releng issue. | <!-- Does this feature require coordination with release engineering (e.g. changes to installer image generation or update package delivery)? Is a mass rebuild required? include a link to the releng issue. | ||
The issue is required to be filed prior to feature submission, to ensure that someone is on board to do any process development work and testing, and that all changes make it into the pipeline; a bullet point in a change is not sufficient communication --> | The issue is required to be filed prior to feature submission, to ensure that someone is on board to do any process development work and testing, and that all changes make it into the pipeline; a bullet point in a change is not sufficient communication --> | ||
| Line 129: | Line 129: | ||
Users that build their packages will experience slightly longer build times. | Users that build their packages will experience slightly longer build times. | ||
[[Category: | [[Category:ChangeAnnounced]] | ||
<!-- When your change proposal page is completed and ready for review and announcement --> | <!-- When your change proposal page is completed and ready for review and announcement --> | ||
<!-- remove Category:ChangePageIncomplete and change it to Category:ChangeReadyForWrangler --> | <!-- remove Category:ChangePageIncomplete and change it to Category:ChangeReadyForWrangler --> | ||
Revision as of 20:20, 29 May 2019
Switch RPMs to zstd compression
Summary
Binary RPMs are currently compressed with xz level 2. Switching to zstd would increase decompression speed significantly.
Owner
- Name: Daniel Mach
- Email: dmach@redhat.com
Current status
- Targeted release: Fedora 31
- Last updated: 2019-05-29
- Tracker bug: <will be assigned by the Wrangler>
- Release notes tracker: <will be assigned by the Wrangler>
Detailed Description
- The change requires setting a new compression algorithm in rpm macros. Then a mass rebuild of all packages is required.
- The macro for setting the compression is: %define _binary_payload w19.zstdio
- The recommended compression level is 19. The builds will take longer, but the additional compression time is negligible in the total build time and it pays off in better compression ratio than xz lvl2 has.
- SRPM payload compression should stay at gzip (there's almost no benefit in changing the compression, because SRPM's contents is compressed already)
Use case: Firefox installation
I rebuilt firefox-66.0.5-1.fc30 with zstd level19. Then I compared installation times with the original (xz compressed) package:
| Compression | Target File System | Time |
|---|---|---|
| xz level 2 | tmpfs | 8s |
| xz level 2 | ext4 on nvme | 11s |
| zstd level 19 | tmpfs | 2s |
| zstd level 19 | ext4 on nvme | 4s |
Comparison of compression algorithms and levels
Following table shows cpio and compressed cpio extraction times into a tmpfs. Actual times in decompressing RPMs will differ due to extracting on an actual disk and also some overhead in the RPM tool (checks, scriptlets).
| Compression | Level | Size B | Size GiB | Compression time | Compression time, 4 threads | Decompression time | Comment |
|---|---|---|---|---|---|---|---|
| CPIO | - | 5016785692 | 4,7 | - | - | - | |
| xz | 2 | 1615017616 | 1,6 | 9m55s | - | 1m36s | slow decompression |
| pxz | 2 | 1631869880 | 1,6 | - | 6m11s | 1m38s | slow decompression |
| gzip | 9 | 2086354992 | 2,0 | 10m23s | - | 31s | insufficient compression ratio |
| bzip2 | 9 | 1889161565 | 1,8 | 8m | - | 2m50s | very slow decompression; compression ratio could be better |
| zstd | 3 | 1913536587 | 1,8 | 31s | 29s | 6,5s | |
| zstd | 10 | 1737928978 | 1,7 | 3m27s | 2m34s | 6,3s | |
| zstd | 15 | 1717303256 | 1,7 | 9m37s | 6m34s | 6,3s | identical compression speed to xz; fast decompression; slightly worse compression ratio than xz |
| zstd | 17 | 1635525492 | 1,6 | 16m16s | 11m20s | 6,7s | |
| zstd | 19 | 1575843696 | 1,5 | 24m2s | 18m55s | 7,7s |
Benefit to Fedora
- Faster installations/upgrades of user systems
- Faster koji builds (installations in build roots)
- Faster container builds
- Lower bandwidth on mirrors if we choose the highest compression level
Scope
- Proposal owners: submit a patch to redhat-rpm-config
- Other developers: redhat-rpm-config maintainer: include the patch and make a new build
- Release engineering: #8395 mass rebuild is needed
- Policies and guidelines: not needed for this Change
- Trademark approval: N/A (not needed for this Change)
Upgrade/compatibility impact
- RPM in Fedora supports zstd compression already (from Fedora 28, rpm-4.14.0-0.rc2.5.fc28). No impact on Fedora users is expected.
- Fedora <= 27 and some other distros will not be able to decompress zstd-compressed RPMs.
How To Test
- dnf install <package>
- rpm -q --qf "%{PAYLOADCOMPRESSOR} %{PAYLOADFLAGS}\n" <package>
- expected output: zstd 19
Also the overall system installation time should decrease significantly.
User Experience
See Benefit to Fedora
Dependencies
N/A
Contingency Plan
- Contingency mechanism: Not needed, Fedora will stay at current compression.
- Contingency deadline: N/A
- Blocks release? No
- Blocks product? N/A
Documentation
N/A
Release Notes
RPMs have switched to zstd compression level 19. Users will benefit from faster package decompression. Users that build their packages will experience slightly longer build times.