Whilst download size is larger, it is at no additional cost to our end users, especially in the cloud. Majority of our clouds offer free transfers inside the availability zone for which mirrors are provided. Obviously it will increase the disk/cache storage size requirements of our mirrors.
Our end users have about 3 sets of kernels installed on disk, for which they do pay more per GB between 2 to 12 cents (depending on technology IOPS / hdd / sda / nvme). All things being equal our users would choose larger download sizes to gain smaller install size. I assume that we have vastly larger install base, compared to number of our mirrors. I also hope that our install base is not larger than the total bandwidth available of our mirrors, such that this switch would cause collapse of our mirror network. I also notice that kernel uses default options for zstd module compression, instead of using -19 like it recommends for the initrds. I also notice that kmod in focal doesn't support zstd. Imho we should fix above before turning this on. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1932329 Title: Benchmark if we can compress kernel modules Status in linux package in Ubuntu: In Progress Bug description: Symbol: MODULE_COMPRESS_ZSTD [=n] Type : bool = Impacts to measure and observe = == Disk space == * Inspect linux-modules-* and linux-modules-extra* deb package Installed-Size and Download-Size changes, i.e. $ apt show linux-modules-5.8.0-53-generic linux-modules- extra-5.8.0-53-generic | grep -e Package: -e Size: Package: linux-modules-5.8.0-53-generic Installed-Size: 81.5 MB Download-Size: 15.5 MB Package: linux-modules-extra-5.8.0-53-generic Installed-Size: 215 MB Download-Size: 41.5 MB In theory, there should not be a significant change in the Download- size. It is desired that there is a significant reduction in Installed-Size. Modules take up about 300MB and normally one has upto three kernel version installed, resulting in about of 1GB of disk space that one constantly pays for. == Boot Speed == In theory, boot speed may either improve or regress. It depends if disk IO is slower than decompression speed, meaning loading compressed modules is faster. Also one has to observe the changes in the initrd size. zstd(zstd) compression may result in slight growth, which shouldn't impact boot speed too much. = Outcomes = If installed size savings can be achieved without regressing bootspeed we should enable CONFIG_MODULE_COMPRESS_ZSTD=y by default. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1932329/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
