Re: First Git status takes 40+ minutes, when mounting fileystem/diskimage with 50G GIT repo + 900G of builds articles

From: Johannes Sixt <j6t@kdbg.org>
Date: Aug 22, 2019, 19:15 UTC
Message-ID: <b409d16f-c392-7f1f-79a0-e14e70148cad@kdbg.org>
In-Reply-To: <2303C0BB-C532-4560-8BCA-A05DAD97EB72@cisco.com>

Am 22.08.19 um 20:02 schrieb Saravanan Shanmugham (sarvi):

Show 6 quoted lines

> We have a diskimage/fileysystem that has a 50G Git repository + 900G
> of binary/build articles and untracked files. When we mount such a
> diskimage, The verify first “git status” command can take as long
> 40-50minutes. Subsequent “git status” finish in under 5-10 seconds.>
> If I had a diskimage of just the 50G source repository, and I mount
> and do a “git status” takes around 15 seconds.

Are you saying that you commonly mount and unmount the filesystem?

Git tracks a device number in the index. Could it happen that it is different every time you mount the filesystem? Because when it is, Git reads the data and checks whether it has changed. At this time, the device number is also fixed up in the index. Thereafter, "git status" is fast because it sees from the cached file properties that no change was made and does not have to read the data.

You may set "git config core.checkStat minimal" to avoid the problem. But it may come with its own problems (certain kinds of modifications would not be noticed, although these would be hard to trigger in practice).

-- Hannes