On 11/19/20 4:01 AM, Ævar Arnfjörð Bjarmason wrote:
The major downside is that detecting the file system type is quite platform-dependent, so there is no simple and portable solution. (Also, I'm not sure if the optimal number of workers would be the same on different OSes). But we decided to give it a try, so this is a rough prototype that would work for Linux: https://github.com/matheustavares/git/commit/2e2c787e2a1742fed8c35dba185b7cd208603de9I'm not intrinsically opposed to hardcoding some "nr_threads = is_nfs() ? x : y" as a stopgap. I do think we should be thinking about a sustainable way of doing this sort of thing, this method of testing once and hardcoding something isn't a good approach. It doesn't anticipate all sorts of different setups, e.g. in this case NFS is not a FS, but a protocol, there's probably going to be some implementations where parallel is much worse due to a quirk of the implementation. I think integrating an optimization run with the relatively new git-maintenance is a better way forward. You'd configure e.g.: maintenance.performanceTests.enabled=true maintenance.performanceTests.writeConfig=true Which would run e.g.: git config --type bool core.untrackedCache $(git update-index --test-untracked-cache && echo true || echo false) git config checkout.workers $(git maintenance--helper auto-discover-config checkout.workers) Such an implementation can be really basic at first, or even just punt on the test and use your current "is it NFS?" check. But I think we should be moving to some helper that does the actual test locally when asked/configured by the user, so we're not making a bunch of guesses in advance about the size/shape of the repository, OS/nfs/fs etc.
I kinda like this idea. It would give us a chance to let maintenance periodically probe the repo/system and improve some of these tuning knobs. Jeff
