Subject: Re: how to speed up "git log"?

From: Bruno Haible <[email-masked]>
Date: Mon, 12 Feb 2007 00:52:23 +0100

Alex Riesen wrote:
> - do not use "tr.c", unless you really need it: git has to read more
>   of a commit in this case. Just "git log" takes only 0.9 sec on the
>   machine above.

"git log" is indeed faster, but is useless for the given task, since it doesn't
show which of the 4 megabytes of commit messages apply to tr.c.

> > On a file in a local copy of the coreutils git repository,
> > "git log tr.c > output" takes
> 
> Why do you need _all_ commits, btw?

I want to quickly find the cause of a behaviour change between tr.c of
coreutils 5.2.1 and the one of coreutils 6.4. It's a period of 1.5 years,
but limited to a single file. Can't git produce this quickly?

> > 2) Why so much system CPU time, but only on MacOS X?
> 
> MacOS X is famous for its bad perfomance when doing serious work.
> The mmap(2) of it, in particular.

But at least, a MacOS X machine is still interactively usable when it uses
6 times more swap than the machine's RAM size. Whereas a Linux 2.4 machine
is interactively unusable already with 1.5 to 2 times more swap than the
machine has RAM.

Bruno