On Tue, 10 Nov 2020 19:05:31 GMT, Aleksey Shipilev <sh...@openjdk.org> wrote:
> It is > [possible](https://github.com/openjdk/jdk/blob/master/doc/building.md#creating-and-using-sysroots-with-qemu-deboostrap) > to efficiently cross-compile to foreign architectures on current GH actions > that are driven by Ubuntu. I have been using this method for years to produce > binaries at [builds.shipilev.net](https://builds.shipilev.net). > > These cross-compilation targets frequently find arch-specific build bugs. > Hotspot is rather well insulated from the fundamental problems in > arch-support, so the overwhelming majority of those arch-specific bugs are > simple omissions of `#include`-s, inconsistent `#ifdef`-ing, missed method > renames / signature changes, or incorrect removals of methods that are used > by arch-specific code. Those are straightforward to fix, if the contributor > knows about them. My experience says the common attitude to these fixes is: > "Oh, I would have fixed it in the original change if I knew about this." > > This improvement adds several foreign architectures to GH actions workflow to > provide the automatic safety net to give early warning for these cases. In > fact, many Hotspot contributors already build AArch64, ARM, PPC64 targets as > pre-integration sanity checks, and this does the important checks > automatically for them. > > To optimize workflow costs, the change does the following: > - The build is only done for hotspot-debug-no-pch, as the most frequent > place where arch-specific build bugs show up. > - There are no tests, and in fact the arch-specific binary does not even > run. The build is purely about the build. > - Foreign architectures reuse the Linux x86_64 release build as build JDK. > This avoids building "host" build JDK as it would otherwise happen with > cross-compiling. > - The created sysroot is cached and keyed on `submit.yml` hash. So it would > regenerate only if the workflow itself changes. This saves about 10 minutes > per arch. > > Space-wise, sysroots in GH cache take about 580M uncompressed, and 270M > zstd-compressed bundle. In the end, this adds 4x270 = 1080M into local cache. > > Time-wise, ball-parking the current workflow budget [looks like > this](https://github.com/shipilev/jdk/runs/1389151071): > - Linux x86_64: > - builds: 120m > - tests: 200m > - Linux x86_32: > - builds: 75m > - tests: 235m > - Windows x86_64 > - builds: 120m > - tests: 290m > - MacOS x86_64 > - builds: 75m > - tests: 165m > - Linux aarch64: > - builds: 25m (+10m to create uncached sysroot) > - Linux arm: > - builds: 20m (+10m to create uncached sysroot) > - Linux ppc64le: > - builds: 20m (+15m to create uncached sysroot) > - Linux s390x: > - builds: 20m (+10m to create uncached sysroot) > > In other words, new workflow takes about 715 Linux-host-minutes, 410 > Windows-host-minutes, 240 Mac-host-minutes. Out of which new jobs take about > 85 Linux-host-minutes. So the cost of new jobs is roughly: > - 11.9% of Linux-host-minutes > - 6.2% of all-host-minutes > - 2.2% of runner-minutes, if you [weigh in the proportional cost of > non-Linux > runners](https://docs.github.com/en/free-pro-team@latest/github/setting-up-and-managing-billing-and-payments-on-github/about-billing-for-github-actions) > > In other words, the additional runner costs are pale in comparison with what > is already done in build and test jobs. This pull request has now been integrated. Changeset: e9956fec Author: Aleksey Shipilev <sh...@openjdk.org> URL: https://git.openjdk.java.net/jdk/commit/e9956fec Stats: 557 lines in 1 file changed: 556 ins; 0 del; 1 mod 8256127: Add cross-compiled foreign architectures builds to submit workflow Reviewed-by: ihse, rwestberg ------------- PR: https://git.openjdk.java.net/jdk/pull/1147
