Re: Change set based shallow clone

From: Jon Smirl <jonsmirl@gmail.com>
Date: Sep 10, 2006, 21:00 UTC
Message-ID: <9e4733910609101400j2604ace1vdb2e363c1296418f@mail.gmail.com>
In-Reply-To: <Pine.LNX.4.64.0609101254590.27779@g5.osdl.org>

On 9/10/06, Linus Torvalds <torvalds@osdl.org> wrote:

Show 8 quoted lines

> On Sun, 10 Sep 2006, linux@horizon.com wrote:
> >
> > A direct fork() (or even faster, vfork) and exec() is going to have a
> > lot less overhead, although it's more work to code.  See Stevens for
> > excellent examples.
>
> Well, that said, the Linux fork/exec/exit is certainly fairly efficient,
> but nothing can hide the fact that it _is_ a very expensive operation.

cvs2svn + fastimport can import the same Mozilla repo in about 2hrs that was taking parsecvs about five days to do. The algorithms are not that different, cvs2svn is probably slower than parsecvs for detecting changesets. The difference is mostly due to the removal of forks.

Is the kernel mapped into user processes using huge pages? That would reduce some of the pressure on TLBs. Another thing that should be mapped with huge pages is the video RAM.

-- 
Jon Smirl
jonsmirl@gmail.com