Re: [Xen-devel] [PATCH] ioemu: Clone ioemu with --depth=1

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2011-11-01 at 18:16 -0400, Jean Guyader wrote:
> On 1 November 2011 21:52, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> > On Tue, 2011-11-01 at 17:32 -0400, Daniel De Graaf wrote:
> >> On 11/01/2011 01:33 PM, Jean Guyader wrote:
> >> >
> >> > Signed-off-by: Jean Guyader <jean.guyader@xxxxxxxxxx>
> >> >
> >> > diff --git a/tools/Makefile b/tools/Makefile
> >> > index 9389e1f..6c1dfe0 100644
> >> > --- a/tools/Makefile
> >> > +++ b/tools/Makefile
> >> > @@ -92,7 +92,7 @@ ioemu-dir-find:
> >> >             if [ ! -d ioemu-remote ]; then \
> >> >                     rm -rf ioemu-remote ioemu-remote.tmp; \
> >> >                     mkdir ioemu-remote.tmp; rmdir ioemu-remote.tmp; \
> >> > -                   $(GIT) clone $(CONFIG_QEMU) ioemu-remote.tmp; \
> >> > +                   $(GIT) clone --depth=1 $(CONFIG_QEMU) 
> >> > ioemu-remote.tmp; \
> >> >                     if [ "$(QEMU_TAG)" ]; then                      \
> >> >                             cd ioemu-remote.tmp;                    \
> >> >                             $(GIT) branch -D dummy >/dev/null 2>&1 ||:; \
> >>
> >> This will break if QEMU_TAG is pointing to any commit that is more than
> >> one commit away from a branch or tag in the source repository.
> >
> > Good point. We could do e.g. --depth=2000 which takes history back to
> > some time in 2007.
> >
> > On the other hand a full clone takes ~30s and a --depth=2000 takes ~20s
> > (both elapsed wallclock times) so it's not clear that there is all that
> > much benefit in the context of how long everything actually takes to
> > build, especially given the big clone only happens once per build tree.
> >
> 
> I don't think it's fair to measure things in seconds here since it's very much
> depend on the Internet connection people are using. When building tip
> of xen-unstable we are actually downloading 3 times as much data that we 
> actually need
> (9.9M instead of 29.11M).

Fair enough.

> I figured that if we don't need to download everything to build we
> shouldn't. I submitted a patch
> because I ended up downloading the tree manually to speed thing up,
> but if you think my patch isn't
> appropriate that is fine.

If we can resolve the issue which Daniel points out then I have no
problem with it conceptually.

> I think this sort of patch would have a much bigger impact when we are
> cloning the Linux kernel.

Note that the Xen build system doesn't clone a Linux kernel any more.

Ian.



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