From d58cbf34ab2200aac62b71d8d46153cad3c4fb99 Mon Sep 17 00:00:00 2001 From: Joey Hess Date: Wed, 10 Jan 2018 15:00:11 -0400 Subject: [PATCH] devblog --- ...3__faster_start_with_removable_drives.mdwn | 27 +++++++++++++++++++ 1 file changed, 27 insertions(+) create mode 100644 doc/devblog/day_483__faster_start_with_removable_drives.mdwn diff --git a/doc/devblog/day_483__faster_start_with_removable_drives.mdwn b/doc/devblog/day_483__faster_start_with_removable_drives.mdwn new file mode 100644 index 0000000000..dfbba15eff --- /dev/null +++ b/doc/devblog/day_483__faster_start_with_removable_drives.mdwn @@ -0,0 +1,27 @@ +git-annex does a little bit of work at startup to learn about the git +repository it's running in. That's been optimised some before, but +not entirely eliminated; it's just too useful to have that information +always available inside git-annex. But it turned out that it was doing more work +than needed for many commands, by checking the git config of local remotes. +Thas caused unncessary spin up of removable drives, or automount timeouts, +or generally more work than needed when running commands like `git annex +find` and even tab completing git-annex. That's fixed now, so it +avoids checking the git config of remotes except when running commands that +access some remote. + +There's also a new config setting, `remote..annex-checkuuid` that can +be set to false to defer checking the uuid of local repositories until +git-annex actually uses them. That can avoid even more spinup/automounts, +but that config prevents git-annex from transparently handling the case +where different removable drives get mounted to the same place at different +times. + +Speaking of speed, I benchmarked linux kernel mitigation for the meltdown +attack making `git status` 5% slower from a warm cache. It did not +slow down `git annex find` or `git annex find --in remote` enough to be +measured by my benchmark. I expect that git-annex commands that transfer +data are bottlenecked on IO and won't be slowed down appreciably by the +meltdown mitigation either. + +Today's work was sponsored by Jake Vosloo on +[Patreon](https://patreon.com/joeyh/).