On Sunday, January 5, 2020 5:23:12 AM MST Bohdan Khomutskyi wrote: > Summary > > Improve compression ratio of SquashFS filesystem on the installation media. > Owner > > Name: Bohdan Khomutskyi > > Email: bkhomuts@xxxxxxxxxx > Current status > > Targeted release: I propose this change for Fedora 32 > > Last updated: Jan 5 2020 > > Pagure.io issue: https://pagure.io/releng/issue/9127 > > I was unable to create an article in Fedora wiki system. > Detailed Description > > As of Fedora 31, the LiveOS/squashfs.img file on the installation image, is > compressed with default settings of mksquashfs. The standard configuration > is set to XZ algorithm with block size of 128k and BCJ filter enabled. > Those parameters can be adjusted which will lead to a better compression > ratio and/or reduction of the CPU usage at build time. > > This is simple to achieve. Recently, Lorax has gotten support[1] for > adjusting the compression options for mksquashfs via the configuration > file. The file should be altered as following: > > [compression] > bcj = yes > args = -b 1M -Xdict-size 1M -no-recovery > > Where -b 1M and -Xdict-size 1M are block and dictionary sizes respectively. > Could be adjusted. > Benefit to Fedora > > - > > Reduction of the installation media size and the cost of storing and > distributing Fedora. > - > > Reduction of the CPU usage at build time. Depending on which compression > parameters chosen. > - > > See a graphical detail at https://pagure.io/releng/issue/9127. > > Scope > > - > > Proposal owners: > > The build environment should have support for adjusting the Lorax > configuration file.. Lorax is a program that produces the > LiveOS/squashfs.img file on the installation media. > > One of the way to allow for such customization, is to add a feature in > Pungi, to allow for passing -c option to Lorax. > > - > > Release engineering: #9127 <https://pagure.io/releng/issue/9127> > - > > Policies and guidelines: N/A > - > > Trademark approval: N/A > > Upgrade/compatibility impact > > - > > This change comes at a cost of higher memory usage during the > installation. Based on my personal estimations, this should not be the > issue. Since the decompression should require up to 1MiB per thread. > > User Experience > > - > > Increasing the block size on the current configuration with EXT4 file > system, should increase latency while accessing the EXT4 filesystem. The > exact impact is to be evaluated. > - > > The impact of latency will be reduced, if the plain SquashFS option is > be choosen. > > Dependencies > > - > > N/A > > Contingency Plan > > - > > N/A > > Documentation > https://pagure.io/releng/issue/9127. > > mksquashfs(1) > Release notes See also > > https://pagure.io/releng/issue/8646 > > -- > > Bohdan Khomutskyi > > Release Configuration Management engineer > Red Hat This looks like an excellent Change, especially as these images grow. -- John M. Harris, Jr. Splentity _______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx
