Am 01.09.2016 um 18:22 schrieb Markus Heiser [off-list ref]:

Am 01.09.2016 um 16:29 schrieb Jani Nikula [off-list ref]:

quoted

On Thu, 01 Sep 2016, Jonathan Corbet [off-list ref] wrote:

quoted

On Wed, 24 Aug 2016 15:35:24 +0200
Markus Heiser [off-list ref] wrote:

quoted

With metadata "parallel_read_safe = True" a extension is marked as
save for "parallel reading of source". This is needed if you want
build in parallel with N processes. E.g.:

make SPHINXOPTS=-j4 htmldocs

A definite improvement; applied to the docs tree, thanks.

The Sphinx docs say -jN "should be considered experimental" [1]. Any
idea *how* experimental that is, really? Could we add some -j by
default?

My experience is, that parallel build is only strong on "reading
input" and weak on "writing output". I can't see any rich performance
increase on more than -j2 ... 

Mauro posted [2] his experience with -j8 compared to serial. He
also compares -j8 to -j16:

quoted

PS: on my server with 16 dual-thread Xeon CPU, the gain with a
bigger value for -j was not impressive. Got about the same time as
with -j8 or -j32 there.

I guess he will get nearly the same results with -j2 ;)

If we want to add a -j default, I suggest -j2. 

[2] https://www.mail-archive.com/linux-doc%40vger.kernel.org/msg05552.html

-- Markus --

Sorry, forget to mentioning, that there has been some improvements
to parallel build in Sphinx 1.3 compared to 1.2. But in 1.3.2 they
have also fixed a bug which lets parallel builds hang :-o

https://github.com/sphinx-doc/sphinx/blob/master/CHANGES#L665

This in mind and if we really support down to sphinx 1.2 ... we
should not use any -j default.

IMHO we should get rid of this sphinx 1.2. downward compatibility,
it makes so may problems (e.g. see [3]) ... but we have discussed
this already and I don't want to restart this thread ;-) 

[3] https://www.mail-archive.com/linux-doc%40vger.kernel.org/msg05695.html

-- Markus --

quoted

BR,
Jani.


[1] http://www.sphinx-doc.org/en/stable/invocation.html#invocation-of-sphinx-build

-- 
Jani Nikula, Intel Open Source Technology Center

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