Re: git gc --aggressive led to about 40 times slower "git log --raw"

2014-02-18 9:45 GMT+00:00 Duy Nguyen <pclouds@gmail.com>:

That's what I already mentioned in my first mail is what I used to fix the problem.

Here are some 'hard' numbers, FWIW:

- both ~/scr and swap are on the same SSD;

$ free
             total       used       free     shared    buffers     cached
Mem:       3996748    3800828     195920          0     377176    1078848
-/+ buffers/cache:    2344804    1651944
Swap:      2097148     169760    1927388

git only used up to about 100 MB of VIRT or RSS when I checked, there was an ulimit of "-S -v 1200000".

- this is git version 1.7.10.4 (1:1.7.10.4-1+wheezy1 i386 Debian)

- after my attempted merge (which had conflicts and I had then
cancelled by way of git reset --hard), and then a "git gc", the times
were:

~/scr$ time git log --raw > _THELOG

real 3m7.002s user 2m0.252s sys 1m6.008s

- on a copy:

/dev/shm/scr$ time git repack -a -d -f Counting objects: 34917, done. Delta compression using up to 2 threads. Compressing objects: 100% (27038/27038), done. Writing objects: 100% (34917/34917), done. Total 34917 (delta 13928), reused 0 (delta 0)

real 4m33.193s user 3m42.950s sys 1m13.821s

/dev/shm/scr$ time git log --raw > _THELOG2

real 0m8.276s user 0m7.192s sys 0m1.052s

(not sure why it took 8s here, perhaps I had another process running at the same time? Compare with the "0m4.913s" below.)

/dev/shm/scr$ time g-gc --aggressive Counting objects: 36066, done. Delta compression using up to 2 threads. Compressing objects: 100% (27812/27812), done. Writing objects: 100% (36066/36066), done. Total 36066 (delta 14367), reused 21699 (delta 0) Checking connectivity: 36066, done.

real 5m52.013s user 8m28.652s sys 1m4.308s

/dev/shm/scr$ time git log --raw > _THELOG2

real 1m34.430s user 0m47.291s sys 0m46.615s

/dev/shm/scr$ time git repack -adf Counting objects: 36066, done. Delta compression using up to 2 threads. Compressing objects: 100% (27812/27812), done. Writing objects: 100% (36066/36066), done. Total 36066 (delta 14256), reused 21699 (delta 0)

real 2m32.083s user 1m51.295s sys 1m4.940s

/dev/shm/scr$ time git log --raw > _THELOG3

real 0m4.913s user 0m3.944s sys 0m0.944s

/dev/shm/scr$ du -s .git 43728 .git

- back in the original place:

~/scr$ time git repack -a -d -f Counting objects: 36066, done. Delta compression using up to 2 threads. Compressing objects: 100% (27812/27812), done. Writing objects: 100% (36066/36066), done. Total 36066 (delta 14257), reused 21700 (delta 0)

real 4m6.503s user 3m16.568s sys 1m11.640s

~/scr$ time git log --raw > _THELOG2

real 0m5.002s user 0m4.032s sys 0m0.952s