From: Matt Mackall <mpm@selenic.com>
To: Daniel Barkalow <barkalow@iabervon.org>
Cc: Petr Baudis <pasky@ucw.cz>,
linux-kernel <linux-kernel@vger.kernel.org>,
git@vger.kernel.org, mercurial@selenic.com,
Linus Torvalds <torvalds@osdl.org>
Subject: Re: Mercurial 0.4e vs git network pull
Date: Thu, 12 May 2005 15:29:43 -0700 [thread overview]
Message-ID: <20050512222943.GI5914@waste.org> (raw)
In-Reply-To: <Pine.LNX.4.21.0505121709250.30848-100000@iabervon.org>
On Thu, May 12, 2005 at 05:24:27PM -0400, Daniel Barkalow wrote:
> On Thu, 12 May 2005, Matt Mackall wrote:
>
> > Does this need an HTTP request (and round trip) per object? It appears
> > to. That's 2200 requests/round trips for my 800 patch benchmark.
>
> It requires a request per object, but it should be possible (with
> somewhat more complicated code) to overlap them such that it doesn't
> require a serial round trip for each. Since the server is sending static
> files, the overhead for each should be minimal.
It's not minimal. The size of an HTTP request is often not much
different than the size of a compressed file delta. Here's one of the
indexes from a file in an hg repo:
rev offset length base linkrev p1 p2 nodeid
0 0 2307 0 0 0000000000.. 0000000000.. b6444347c6..
1 2307 77 0 5 b6444347c6.. 0000000000.. 06763db6de..
2 2384 225 0 11 06763db6de.. 0000000000.. acc8e2b2f0..
3 2609 40 0 16 acc8e2b2f0.. 0000000000.. 461b079d98..
4 2649 261 0 17 461b079d98.. 0000000000.. 8507ba44cc..
5 2910 486 0 18 8507ba44cc.. 0000000000.. b68523252b..
6 3396 98 0 21 b68523252b.. 0000000000.. b3f2586243..
7 3494 238 0 22 b3f2586243.. 0000000000.. d73d0f8ee9..
8 3732 39 0 23 d73d0f8ee9.. 0000000000.. caaf506196..
9 3771 266 0 24 caaf506196.. 0000000000.. 54485fc96f..
10 4037 81 0 29 54485fc96f.. 0000000000.. b9eae7b990..
11 4118 310 0 31 b9eae7b990.. 0000000000.. a9926b092a..
12 4428 545 0 33 a9926b092a.. 0000000000.. f26c600172..
13 4973 419 0 34 f26c600172.. 0000000000.. ec4ab0acb7..
14 5392 136 0 38 ec4ab0acb7.. 0000000000.. eb5f3f76c8..
15 5528 161 0 39 eb5f3f76c8.. 0000000000.. 4fc5f3a3ae..
16 5689 258 0 46 4fc5f3a3ae.. 0000000000.. 3ad83891fb..
17 5947 171 0 49 3ad83891fb.. 0000000000.. 3983ac6cd2..
18 6118 195 0 50 3983ac6cd2.. 0000000000.. f138865e04..
19 6313 79 0 52 f138865e04.. 0000000000.. 3566c1f449..
20 6392 85 0 53 3566c1f449.. 0000000000.. 0694a4e3eb..
21 6477 91 0 54 0694a4e3eb.. 0000000000.. 5f98ae7426..
22 6568 208 0 56 5f98ae7426.. 0000000000.. dae5cb80db..
23 6776 286 0 62 dae5cb80db.. 0000000000.. 90ff243869..
All the junk that gets bundled in an http request/response will be
similar in size to the stuff in the third column.
Relative to the 10-20x overhead of not sending deltas, yes, it's only 10%.
> > How does git find the outstanding changesets?
>
> In the present mainline, you first have to find the head commit you
> want. I have a patch which does this for you over the same
> connection. Starting from that point, it tracks reachability on the
> receiving end, and requests anything it doesn't have.
Does it do this recursively? Eg, if the server has 800 new linear
commits, does the client have to do 800 round trips following parent
pointers to find all the new changesets? In this case, Mercurial does
about 6 round trips, totalling less than 1K, plus one requests
that pulls everything.
--
Mathematics is the supreme nostalgia of our time.
next prev parent reply other threads:[~2005-05-12 22:22 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-05-12 9:44 Mercurial 0.4e vs git network pull Matt Mackall
2005-05-12 18:23 ` Petr Baudis
2005-05-12 20:11 ` Matt Mackall
2005-05-12 20:14 ` Petr Baudis
2005-05-12 20:57 ` Matt Mackall
2005-05-12 21:24 ` Daniel Barkalow
2005-05-12 22:29 ` Matt Mackall [this message]
2005-05-13 0:33 ` Daniel Barkalow
2005-05-13 1:11 ` Matt Mackall
2005-05-13 2:23 ` Daniel Barkalow
2005-05-13 2:44 ` Matt Mackall
2005-05-13 5:44 ` Petr Baudis
2005-05-15 8:54 ` Petr Baudis
2005-05-15 6:22 ` Ingo Molnar
-- strict thread matches above, loose matches on Subject: below --
2005-05-15 11:22 Adam J. Richter
2005-05-15 12:40 ` Petr Baudis
2005-05-16 22:22 ` Tristan Wibberley
2005-05-15 17:39 ` Matt Mackall
2005-05-15 18:23 ` Jeff Garzik
2005-05-16 1:12 ` Matt Mackall
2005-05-16 9:29 ` Matthias Urlichs
2005-05-15 11:52 Adam J. Richter
2005-05-15 14:23 ` Petr Baudis
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