[PATCH] [DOCS] How to Add a Builder

[Mikael Lyngvig]

Okay, let's drop my patch - it was not well thought out.  Sorry about that
:-)  I'd like to document the "Clean=false" feature somewhere, though, but
right now I am overloaded with tasks.

-- Mikael


2013/11/14 Rick Foos <rfoos at codeaurora.org>

> I’ve used CCache, but I thought it might be controversial. It is not
> limited to low end systems. My 6 minute clang build goes down to 40 to  50
> seconds.
>
>
>
> While the sources are updated, the make cleans clear things out. Ccache
> takes care of that, and only the 5 or 10 files actually changed are built.
>
>
>
> Not sure that ccache is within the scope of this document.
>
>
>
> Rick
>
>
>
> *From:* llvm-commits-bounces at cs.uiuc.edu [mailto:
> llvm-commits-bounces at cs.uiuc.edu] *On Behalf Of *Mikael Lyngvig
> *Sent:* Thursday, November 14, 2013 12:00 AM
> *To:* Reid Kleckner
> *Cc:* LLVM-commits
> *Subject:* Re: [PATCH] [DOCS] How to Add a Builder
>
>
>
> Perhaps I've misunderstood something.  I thought the builders restarted
> from scratch each and every time so as to ensure that the complete product
> builds reliably.  This to ensure that the project doesn't gradually rot.
>
>
>
> If the builders simply update and remake, then there's absolutely no point
> in using ccache, I agree wholeheartedly to that.
>
>
>
> Is anybody with knowledge of the buildbot system listening in?  Do the
> builders start from scratch each time or do they simply resume and continue
> after having performed an "svn update"?  The build times strongly suggest
> that they start over from scratch, at least some of them.
>
>
>
>
>
> -- Mikael
>
>
>
>
>
>
>
> 2013/11/14 Reid Kleckner <rnk at google.com>
>
> Starting from scratch seems undesirable.  ccache is basically just undoing
> that for you.
>
>
>
> On Wed, Nov 13, 2013 at 9:46 PM, Mikael Lyngvig <mikael at lyngvig.org>
> wrote:
>
> The problem is specific to the buildbot slaves that always start from
> scratch.  Otherwise, I agree with your views.
>
>
>
>
>
> -- Mikael
>
>
>
> 2013/11/14 Reid Kleckner <rnk at google.com>
>
> IMO ccache is unnecessary if you use cmake+ninja.  They actually track
> header dependencies well, so as long as you don't clean your build
> directory, you'll have fast, correct incremental builds.  ccache won't save
> much in that situation because the preprocessed source will actually be
> different.
>
>
>
> On Wed, Nov 13, 2013 at 9:12 PM, Mikael Lyngvig <mikael at lyngvig.org>
> wrote:
>
> Hi,
>
>
>
> The patch basically tells that ccache is very usable for low-end Linux
> systems and briefly how to get going using ccache (one special option is
> needed, thanks to Dimitri Gribenko, for sharing this).
>
>
>
> On my ARMv7 a repeat clean build takes less than 1/3rd the time of the
> initial clean build.  So it is definitely something that the slow builders
> can benefit from.  A build time of 36 minutes was reduced to approximately
> 11.5 minutes.
>
>
>
> I suspect it might better be put in the GettingStarted document, but I
> need feedback on this.
>
>
>
> If anybody dislikes the idea of putting this patch in the LLVM
> documentation, then please think of the fact that LLVM benefits greatly
> from the builders doing their job as fast as at all possible.
>
>
>
>
>
> -- Mikael
>
>
>
>
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