From: Alex Riesen <fork0@users.sourceforge.net>
To: Git Mailing List <git@vger.kernel.org>
Cc: Junio C Hamano <junkio@cox.net>,
Linus Torvalds <torvalds@osdl.org>,
Christopher Faylor <me@cgf.cx>, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: First cut at git port to Cygwin
Date: Fri, 7 Oct 2005 23:22:50 +0200 [thread overview]
Message-ID: <20051007212250.GA1423@steel.home> (raw)
In-Reply-To: <20051007205450.GA14827@steel.home>
Alex Riesen, Fri, Oct 07, 2005 22:54:50 +0200:
> Linus Torvalds, Fri, Oct 07, 2005 17:34:19 +0200:
> > > it suddenly get worse: now I'm stuck on git-pull.
> > >
> > > git-merge-index (called at some point by git-pull) maps the index
> > > in, and starts git-merge-one-file for each (or the given) entry in
> > > the index. git-merge-one-file calls git-update-index, which wants
> > > to update the index. Which doesn't work, because it's locked by
> > > that piece of s$%^.
> >
> > NOTE! git doesn't use mmap() because it _needs_ to use mmap(), but because
> > it was simple to do that way, and it's a total idiosyncracy of mine that I
> > often try to mmap the data. I often also tend to do my own allocators
> > instead of using malloc() (see my "sparse" project in case you're
> > interested in other idiosyncracies of mine - macros to do list traversal
> > etc).
> >
> > The fact is, "mmap()" isn't really any better than "read()": it has some
> > advantages wrt memory management for the kernel, which is probably one big
> > reason why I do it, but quite frankly, if you were to change every single
> > mmap() to be a "map_file()" instead, and made it optional whether it used
> > mmap() or "malloc + read()", I personally don't think it would be
> > horrible.
> >
> > And it might make things much simpler for portability. The "use mmap"
> > approach is very much a unixism, particularly the way unix people do it
> > (mmap followed by close, making the file descriptor "go away"). Sure,
> > other OS's have mmap too, but I think on them it tends to be less commonly
> > used.
>
> "Sounds like a thinly veiled threat or a very effective prodding" 8)
>
Junio C Hamano, Fri, Oct 07, 2005 23:00:02 +0200:
> Huh? where is your memcpy?
Unbelievable... I actually tested the change! But not _the_ patch.
Thanks. Next time, hit me :)
---
Make read_cache copy the index into memory, to improve portability on
other OS's which have mmap too, tend to use it less commonly.
Signed-off-by: Alex Riesen <raa.lkml@gmail.com>
diff --git a/read-cache.c b/read-cache.c
--- a/read-cache.c
+++ b/read-cache.c
@@ -497,9 +497,12 @@ int read_cache(void)
offset = sizeof(*hdr);
for (i = 0; i < active_nr; i++) {
struct cache_entry *ce = map + offset;
- offset = offset + ce_size(ce);
- active_cache[i] = ce;
+ size_t size = ce_size(ce);
+ struct cache_entry *newce = malloc(size);
+ offset = offset + size;
+ active_cache[i] = memcpy(newce, ce, size);
}
+ munmap(map, size);
return active_nr;
unmap:
next prev parent reply other threads:[~2005-10-07 21:23 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-29 0:53 First cut at git port to Cygwin H. Peter Anvin
2005-09-29 4:30 ` Junio C Hamano
2005-09-29 5:07 ` H. Peter Anvin
2005-09-29 4:46 ` Martin Langhoff
2005-09-29 5:13 ` Junio C Hamano
2005-09-29 6:19 ` H. Peter Anvin
2005-09-29 8:46 ` Johannes Schindelin
2005-09-29 16:11 ` H. Peter Anvin
2005-09-29 17:25 ` H. Peter Anvin
2005-09-30 10:02 ` Junio C Hamano
2005-09-30 17:01 ` H. Peter Anvin
2005-09-30 19:08 ` H. Peter Anvin
2005-10-04 12:31 ` Alex Riesen
2005-10-04 13:06 ` Alex Riesen
2005-10-04 14:06 ` H. Peter Anvin
2005-10-05 3:15 ` Christopher Faylor
2005-10-04 15:03 ` H. Peter Anvin
2005-10-05 3:16 ` Christopher Faylor
2005-10-05 5:25 ` H. Peter Anvin
2005-10-05 11:24 ` Alex Riesen
2005-10-05 15:46 ` Alex Riesen
2005-10-05 15:54 ` Christopher Faylor
2005-10-05 16:09 ` Davide Libenzi
2005-10-05 16:15 ` Christopher Faylor
2005-10-05 16:23 ` H. Peter Anvin
2005-10-05 16:28 ` Christopher Faylor
2005-10-05 17:29 ` Davide Libenzi
2005-10-05 19:17 ` Alex Riesen
2005-10-05 20:29 ` Christopher Faylor
2005-10-06 9:05 ` Alex Riesen
2005-10-06 10:07 ` Alex Riesen
2005-10-07 12:44 ` Alex Riesen
2005-10-07 15:34 ` Linus Torvalds
2005-10-07 20:54 ` Alex Riesen
2005-10-07 21:22 ` Alex Riesen [this message]
2005-10-07 21:29 ` Chuck Lever
2005-10-07 21:39 ` Alex Riesen
2005-10-08 16:11 ` Linus Torvalds
2005-10-08 17:38 ` Elfyn McBratney
2005-10-08 17:43 ` Elfyn McBratney
2005-10-08 18:27 ` Johannes Schindelin
2005-10-08 18:44 ` Junio C Hamano
2005-10-08 19:04 ` Johannes Schindelin
2005-10-08 21:10 ` Junio C Hamano
2005-10-08 22:06 ` Johannes Schindelin
2005-10-10 18:43 ` H. Peter Anvin
2005-10-10 19:01 ` Johannes Schindelin
2005-10-10 19:26 ` H. Peter Anvin
2005-10-10 19:42 ` Johannes Schindelin
2005-10-10 20:21 ` Junio C Hamano
2005-10-10 20:34 ` Junio C Hamano
2005-10-10 20:52 ` H. Peter Anvin
2005-10-10 20:27 ` Daniel Barkalow
2005-10-08 18:49 ` Alex Riesen
2005-10-09 20:40 ` Commit text BEFORE the dashes (Re: First cut at git port to Cygwin) Matthias Urlichs
[not found] ` <7vfyrdyre5.fsf@assigned-by-dhcp.cox.net>
2005-10-07 23:45 ` First cut at git port to Cygwin Alex Riesen
2005-10-08 1:00 ` Elfyn McBratney
2005-10-10 18:45 ` H. Peter Anvin
2005-10-05 13:16 ` Jonas Fonseca
2005-10-05 13:58 ` Johannes Schindelin
2005-10-05 15:52 ` [PATCH] Fix symbolic ref validation Jonas Fonseca
2005-10-05 16:54 ` Junio C Hamano
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