tree d81f3de59393e27d084d010e68c9f6f1b10fefa3
parent 8fc67762471c60ee644e6e100a3a85cf5a8631a0
author Nguyễn Thái Ngọc Duy <pclouds@gmail.com> 1523806577 +0200
committer Junio C Hamano <gitster@pobox.com> 1523854349 +0900

gc --auto: exclude base pack if not enough mem to "repack -ad"

pack-objects could be a big memory hog especially on large repos,
everybody knows that. The suggestion to stick a .keep file on the
giant base pack to avoid this problem is also known for a long time.

Recent patches add an option to do just this, but it has to be either
configured or activated manually. This patch lets `git gc --auto`
activate this mode automatically when it thinks `repack -ad` will use
a lot of memory and start affecting the system due to swapping or
flushing OS cache.

gc --auto decides to do this based on an estimation of pack-objects
memory usage, which is quite accurate at least for the heap part, and
whether that fits in half of system memory (the assumption here is for
desktop environment where there are many other applications running).

This mechanism only kicks in if gc.bigBasePackThreshold is not configured.
If it is, it is assumed that the user already knows what they want.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>