On Sat, Sep 11, 2021 at 7:14 AM Zbigniew Jędrzejewski-Szmek <zbyszek@xxxxxxxxx> wrote: > > On Tue, May 04, 2021 at 12:46:33PM +0100, Richard W.M. Jones wrote: > > On Mon, May 03, 2021 at 08:51:15PM -0000, Reon Beon via devel wrote: > > > LINUX KERNEL -- > > > Adding to the variety of places where the Linux kernel supports making use of Zstd compression, kernel modules moving forward can now enjoy size reductions with Zstd. > > > > Is this email a proposed Fedora change? Might be best to follow the > > process: > > > > https://docs.fedoraproject.org/en-US/program_management/changes_policy/ > > > > This change, while probably welcome, isn't entirely confined to the > > kernel package. Various other packages consume/create kernel modules > > and so will be affected. (In my case, supermin will require small > > changes to cope.) So it should be submitted as a system-wide change > > IMHO. > > I decided to take a stab at this. Draft PR: > https://gitlab.com/cki-project/kernel-ark/-/merge_requests/1379 > > I'll paste the commit message, it has a bunch of measurements: > > rpmspec: switch to zstd compression for modules > > The main advantage is that zstd decompression is a lot faster and requires less > memory than lzma. This means that we need less CPU when loading various modules > and boot is a bit snappier. > > All tests done with zstd-1.5.0-1.fc33.x86_64. > > kmod >= 28 supports zstd, and 29 is present in all Fedora releases, so no dependency > needs to be specified. > > The compression is reduced a bit, so we pay some price in terms of disk space: > $ du -c **/*.ko|tail -n1 290148 total > $ du -c **/*.ko.xz|tail -n1 64324 total > $ du -c **/*.ko.zst|tail -n1 82560 total # default compression > $ du -c **/*.ko.zst|tail -n1 71152 total # with -19 > > Decompression of a bunch of drivers (serial, 133 files, from cache, no disk io): > $ time xzcat drivers/net/wireless/**/*.xz >/dev/null > xzcat drivers/net/wireless/**/*.xz > /dev/null 8.46s user 0.07s system 99% cpu 8.562 total > $ time zstdcat drivers/net/wireless/**/*.zst >/dev/null > zstdcat drivers/net/wireless/**/*.zst > /dev/null 1.33s user 0.05s system 99% cpu 1.396 total > > (Max RSS is about 2×higher with xz). > > So I'd say that we can expect some speedup when booting a machine, but not something > that would blow people away. > > Benchmarking of compression with a subset of files (drivers/net/wireless only): > > $ for i in {1..20}; do rm **/*.ko.zst; time parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko; du -c **/*.ko.zst|tail -n1; done > parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko 3.80s user 1.21s system 710% cpu 0.705 total > 147392 total > parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko 4.04s user 1.28s system 724% cpu 0.735 total > 133768 total > parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko 6.30s user 1.45s system 838% cpu 0.925 total > 129656 total > parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko 9.67s user 1.76s system 914% cpu 1.249 total > 128636 total > parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko 13.58s user 2.10s system 957% cpu 1.639 total > 126944 total > parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko 13.44s user 2.00s system 929% cpu 1.661 total > 126056 total > parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko 15.59s user 1.92s system 920% cpu 1.901 total > 118472 total > parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko 17.79s user 1.84s system 955% cpu 2.054 total > 115300 total > parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko 22.84s user 2.24s system 960% cpu 2.611 total > 114384 total > parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko 25.50s user 2.99s system 988% cpu 2.881 total > 114060 total > parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko 27.75s user 3.86s system 993% cpu 3.182 total > 114016 total > parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko 35.74s user 3.93s system 961% cpu 4.127 total > 113828 total > parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko 62.49s user 3.05s system 1009% cpu 6.489 total > 114272 total > parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko 64.67s user 4.07s system 1009% cpu 6.809 total > 114160 total > parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko 81.46s user 4.88s system 1004% cpu 8.594 total > 114284 total > parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko 141.48s user 3.71s system 1014% cpu 14.316 total > 111920 total > parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko 155.15s user 4.33s system 1017% cpu 15.681 total > 110744 total > parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko 197.08s user 4.52s system 1014% cpu 19.880 total > 101576 total > parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko 223.10s user 5.79s system 1018% cpu 22.475 total > 101616 total > parallel zstd -q -$i ::: drivers/net/wireless/**/*.ko 223.40s user 5.84s system 1018% cpu 22.498 total > 101616 total > > (-20 is the same as -19, unless --ultra is used, which it wasn't here.) > > $ for i in {0..9}; do rm **/*.ko.xz; time parallel xz -q -k -$i ::: drivers/net/wireless/**/*.ko; du -c **/*.ko.xz|tail -n1; done > parallel xz -q -k -$i ::: drivers/net/wireless/**/*.ko 34.50s user 1.05s system 992% cpu 3.583 total > 105124 total > parallel xz -q -k -$i ::: drivers/net/wireless/**/*.ko 46.20s user 1.58s system 1013% cpu 4.715 total > 96704 total > parallel xz -q -k -$i ::: drivers/net/wireless/**/*.ko 58.17s user 2.05s system 1027% cpu 5.859 total > 95236 total > parallel xz -q -k -$i ::: drivers/net/wireless/**/*.ko 71.78s user 2.88s system 1029% cpu 7.254 total > 94872 total > parallel xz -q -k -$i ::: drivers/net/wireless/**/*.ko 205.66s user 3.77s system 1031% cpu 20.302 total > 90012 total > parallel xz -q -k -$i ::: drivers/net/wireless/**/*.ko 248.38s user 5.69s system 1010% cpu 25.142 total > 86724 total > parallel xz -q -k -$i ::: drivers/net/wireless/**/*.ko 262.77s user 5.44s system 1022% cpu 26.243 total > 86416 total > parallel xz -q -k -$i ::: drivers/net/wireless/**/*.ko 265.86s user 7.62s system 1019% cpu 26.835 total > 86400 total > parallel xz -q -k -$i ::: drivers/net/wireless/**/*.ko 268.05s user 10.74s system 1023% cpu 27.229 total > 86400 total > parallel xz -q -k -$i ::: drivers/net/wireless/**/*.ko 267.98s user 10.28s system 1020% cpu 27.266 total > 86400 total > > Based on this, I selected -18 as the compression level. > > I think it's still worth to pursue — we should see a speedup on > slow-cpu machines and/or machines with hardware that requires a bunch > of modules. > > Koji scratch build: https://koji.fedoraproject.org/koji/taskinfo?taskID=75506561 > > I plan to submit an F36 change for this, as requested. If you'd like > to be a co-owner, please let me know. In particular testing and benchmarking > would be great contributions. So far I only tested this by booting > a VM, though the change seems rather straightforward, so if it works there, > it should work everywhere. > > (In the PR, there's also a second commit to use zstd for kernel rpm > compression, or in other words, to stop overriding the default.) > As discussed previously, there is more to this than just changing the kernel. There are bugs open for kdump, and there were a couple of other pieces which need to be addressed. The lack of zstd modules so far is not about being unwilling to do the work to make it happen, it is a matter that we are not quite ready for it. It is not falling off of the radar. Justin _______________________________________________ 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 Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure
