Hi Duy, On Wed, Nov 25, 2015 at 8:51 PM, Duy Nguyen <pclouds@xxxxxxxxx> wrote: > On Wed, Nov 25, 2015 at 10:00 AM, Ævar Arnfjörð Bjarmason > <avarab@xxxxxxxxx> wrote: >> On Wed, Nov 25, 2015 at 7:35 AM, Christian Couder >> <christian.couder@xxxxxxxxx> wrote: >>> At Booking.com we know that mtime works everywhere and we don't >>> want the untracked cache to stop working when a kernel is upgraded >>> or when the repo is copied to a machine with a different kernel. >>> I will add tests later if people are ok with this. >> >> I bit more info: I rolled Git out internally with this patch: >> https://github.com/avar/git/commit/c63f7c12c2664631961add7cf3da901b0b6aa2f2 >> >> The --untracked-cache feature hardcodes the equivalent of: >> >> pwd; uname --kernel-name --kernel-release --kernel-version >> >> Into the index. If any of those change it prints out the "cache is >> disabled" warning. >> >> This patch will make it stop being so afraid of itself to the point of >> disabling itself on minor kernel upgrades :) > > The problem is, there's no way to teach git to know it's a "minor" > upgrade.. but if there is a config key to say "don't be paranoid, I > know what I'm doing", then we can skip that check, or just warn > instead of disabling the cache. Yeah, in my patch if core.trustmtime is set to true or false the check is skipped. I am wondering why you didn't make it by default run the mtime checks when a kernel change is detected. Maybe that would be better than disabling itself. >> A few other issues with this feature I've noticed: >> >> * There's no way to just enable it globally via the config. Makes it >> a bit of a hassle to use it. I wanted to have a config option to >> enable it via the config, how about "index.untracked_cache = true" for >> the config variable name? > > If you haven't noticed, all these experimental features have no real > UI (update-index is plumbing). I have been waiting for someone like > you to start using it and figure out the best UI (then implement it) > ;) Ok, we are happy to do that (including implementing it) :-) I will take a look at something like index.untracked_cache. It will probably also be a tristate like this: - true: always enable it; die if core.trustmtime is false otherwise warn if it is not true - default/unset: same as current behavior - false: die if it is enabled or when trying to enable to it >> * Doing "cd /tmp: git --git-dir=/git/somewhere/else/.git update-index >> --untracked-cache" doesn't work how I'd expect. It hardcodes "/tmp" as >> the directory that "works" into the index, so if you use the working >> tree you'll never use the untracked cache. I spotted this because I >> carry out a bunch of git maintenance commands with --git-dir instead >> of cd-ing to the relevant directories. This works for most other >> things in git, is it a bug that it doesn't work here? > > It needs the current directory at --untrack-cache time to test if the > directory satisfies the requirements. So either you cd to that > worktree, or you have to specify --worktree as well. Or am I missing > something? Maybe it could print out a message saying "Testing mtime in directory $(pwd)" and if that works then "Untracked cache is enabled for $(pwd)". That would make it clear that it will not work in other directories. Also maybe the mtime checks could be run when a directory change is detected. >> * If you "ctrl+c" git update-index --untracked-cache at an >> inopportune time you'll end up with a mtime-test-XXXXXX directory in >> your working tree. Perhaps this tempdir should be created in the .git >> directory instead? > > No because in theory .git could be on a separate file system with > different semantics. But we should probably clean those files at ^C. Ok, I will have a look at cleaning the files at ^C. >> * Maybe we should have a --test-untracked-cache option, so you can >> run the tests without enabling it. > > I'd say patches welcome. Ok, I wll have a look at that too. >> Aside from the slight hassle of enabling this and keeping it enabled >> this feature is great. It's sped up "git status" across the board by >> about 40%. Slightly less than that on faster spinning disks, slightly >> more than that on slower ones. > > I'm still waiting for the day when watchman support gets merged and > maybe poke Facebook guys to compare performance with Mercurial :) > Well, we are probably still behind Mercurial on that day. Yeah, it could be interesting to compare performance with Mercurial as we move forward :-) > Also, there's still work to be done. Right now it's optimized for > whole-tree "git status", Doing "git status -- abc" will not benefit > from untracked cache, similarly "git add" with pathspec.. Thanks for these details. Yeah, it might be interesting to look at "git add" too. Best, Christian. -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html