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Re: svn commit: r1139766 - /subversion/trunk/subversion/svn/main.c

From: Stefan Sperling <stsp_at_elego.de>
Date: Mon, 27 Jun 2011 14:20:18 +0200

On Mon, Jun 27, 2011 at 12:52:37PM +0100, Philip Martin wrote:
> Stefan Sperling <stsp_at_elego.de> writes:
> >> I disagree.
> >>
> >> Upgrade requires more disk IO but requires significantly less network IO
> >> and uses marginally less CPU. Checkout is likely to be faster when disk
> >> IO is the limiting factor, but if network IO is the limiting factor then
> >> checkout could be significantly slower.
> >
> > When I upgraded a 1.6.x working copy of 2GB size, it took more than one hour.
> > I eventually just aborted the upgrade. A checkout completes within
> > a couple of minutes.
> >
> > The repository is remote and the bottleneck should be my 16MB/s downstream
> > link (the server is connected to my ISP via the berlin internet exchange
> > at 100Mbit/s). So based on what you're saying I should be seeing a much
> > better upgrade vs. checkout ratio.
> >
> > Link to the repository: http://svn.dslinux.org/svn/trunk
> >
> > svn also seemed to spend more and more time hogging the CPU as the upgrade
> > progressed. Note: I have not profiled this, it is all based on what I
> > perceived while waiting for the upgrade to complete, and I kept box getting
> > more and more impatiant. I'd be willing to repeat this experiment with a
> > profiled build.
> I don't know why that upgrade is slow, but perhaps you are limited by
> disk IO. Maybe upgrade doesn't scale properly.
> It's wrong to claim that checkout is faster than upgrade
> unconditionally. A checkout of Subversion trunk from Apache takes about
> 10s on my machine, an upgrade takes 5s. That's with a hot cache, with a
> cold cache upgrade takes about 15s. The checkout speed varies,
> sometimes it takes ove 20s. Which one is faster?


What about a note that says that upgrade *might* be slower than checkout?

Index: subversion/svn/main.c
--- subversion/svn/main.c (revision 1140083)
+++ subversion/svn/main.c (working copy)
@@ -1385,7 +1385,7 @@ const svn_opt_subcommand_desc2_t svn_cl__cmd_table
      " Local modifications are preserved.\n"
      " Note: Upgrading a working copy from the format used in Subversion 1.6\n"
- " to the format used in Subversion 1.7 takes much more time than checking\n"
+ " to the format used in Subversion 1.7 might take more time than checking\n"
      " out a new working copy with the 1.7 client.\n"),
     { 'q' } },
Received on 2011-06-27 14:20:53 CEST

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