From: Nicolas Pitre <nico@cam.org>
Date: Wed, 10 Jan 2007 01:12:34 GMT
Subject: Re: [PATCH] Replacing the system call pread() with lseek()/xread()/lseek() sequence.
Message-ID: <Pine.LNX.4.64.0701092010090.4964@xanadu.home>
In-Reply-To: <20070109232540.GA30023@spearce.org>

On Tue, 9 Jan 2007, Shawn O. Pearce wrote:

> Andy Whitcroft <apw@shadowen.org> wrote:
> > How likely are we ever to be in the right place here?  Seems vanishingly
> > small putting us firmly in the four syscalls per call space.  I wonder
> > if git ever actually cares about the seek location.  ie if we could stop
> > reading and resetting it.  Probabally not worth working it out I guess
> > as any _sane_ system has one.
> 
> Andy's right actually.  If we are using pread() we aren't relying
> on the current file pointer.  Which means its unnecessary to get
> the current pointer before seeking to the requested offset, and its
> unnecessary to restore it before the git_pread() function returns.

No this is wrong.  The original offset _has_ to be preserved.  
index-pack counts on it.


Nicolas