From: Shawn Pearce <spearce@spearce.org>
To: Junio C Hamano <junkio@cox.net>
Cc: Linus Torvalds <torvalds@osdl.org>, git@vger.kernel.org
Subject: Re: [PATCH 11/17] Fully activate the sliding window pack access.
Date: Sat, 23 Dec 2006 21:35:30 -0500 [thread overview]
Message-ID: <20061224023530.GC7443@spearce.org> (raw)
In-Reply-To: <7vodpuqtuf.fsf@assigned-by-dhcp.cox.net>
Junio C Hamano <junkio@cox.net> wrote:
> Linus Torvalds <torvalds@osdl.org> writes:
> > Hmm. You seem to default the window size to 32MB.
> >
> > Maybe I'm reading that code wrong, but I think that's a bit sad.
> >
> > So I'd argue that if you fall back to read() (or pread) instead of mmap,
> > the 32MB thing is way too big.
> >
> > So maybe you should make the default depend on NO_MMAP (although it would
> > seem that the default Makefile makes Cygwin actually default to using mmap
> > these days, so maybe it's not a big deal).
>
> I agree that 32MB is too big for emulated mmap().
Yes, I agree too. I'll submit some additional patches on top of
the existing 17 patch series (which I see is already in 'pu').
> We might want
> to further enhance the new use_pack() API so that the caller can
> say how much it expects to consume, to help pread() based
> emulation avoid reading unnecessary data.
I'm not sure that is worthwhile right now.
The only two callers who know how many bytes they expect is
pack-objects (during delta/whole reuse) and verify-pack (during the
SHA1 check of the packfile itself). Both are maintenance commands
where preventing a read overshoot in the case of NO_MMAP is probably
not worthwhile, especially as both need to read every byte anyway.
--
Shawn.
next prev parent reply other threads:[~2006-12-24 2:35 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <53b67707929c7f051f6d384c5d96e653bfa8419c.1166857884.git.spearce@spearce.org>
2006-12-23 7:33 ` [PATCH 1/17] Replace unpack_entry_gently with unpack_entry Shawn O. Pearce
2006-12-23 7:33 ` [PATCH 2/17] Introduce new config option for mmap limit Shawn O. Pearce
2006-12-23 7:33 ` [PATCH 3/17] Refactor packed_git to prepare for sliding mmap windows Shawn O. Pearce
2006-12-23 7:33 ` [PATCH 4/17] Use off_t for index and pack file lengths Shawn O. Pearce
2006-12-23 7:33 ` [PATCH 5/17] Create read_or_die utility routine Shawn O. Pearce
2006-12-23 7:34 ` [PATCH 6/17] Refactor how we open pack files to prepare for multiple windows Shawn O. Pearce
2006-12-23 7:34 ` [PATCH 7/17] Replace use_packed_git with window cursors Shawn O. Pearce
2006-12-23 7:34 ` [PATCH 8/17] Loop over pack_windows when inflating/accessing data Shawn O. Pearce
2006-12-23 7:34 ` [PATCH 9/17] Document why header parsing won't exceed a window Shawn O. Pearce
2006-12-23 7:34 ` [PATCH 10/17] Unmap individual windows rather than entire files Shawn O. Pearce
2006-12-23 7:34 ` [PATCH 11/17] Fully activate the sliding window pack access Shawn O. Pearce
2006-12-23 18:44 ` Linus Torvalds
2006-12-23 19:34 ` Eric Blake
2006-12-24 0:58 ` Johannes Schindelin
2006-12-23 19:45 ` Junio C Hamano
2006-12-23 20:10 ` Linus Torvalds
2006-12-24 1:23 ` Johannes Schindelin
2006-12-24 2:23 ` Shawn Pearce
2006-12-24 2:35 ` Shawn Pearce [this message]
2006-12-23 7:34 ` [PATCH 12/17] Load core configuration in git-verify-pack Shawn O. Pearce
2006-12-23 7:34 ` [PATCH 13/17] Ensure core.packedGitWindowSize cannot be less than 2 pages Shawn O. Pearce
2006-12-23 7:34 ` [PATCH 14/17] Improve error message when packfile mmap fails Shawn O. Pearce
2006-12-23 7:34 ` [PATCH 15/17] Support unmapping windows on 'temporary' packfiles Shawn O. Pearce
2006-12-23 7:34 ` [PATCH 16/17] Create pack_report() as a debugging aid Shawn O. Pearce
2006-12-23 7:34 ` [PATCH 17/17] Test suite for sliding window mmap implementation Shawn O. Pearce
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