Daniel P. Berrangé <berra...@redhat.com> writes:
> On Sat, Apr 29, 2023 at 02:33:17PM +0200, Paolo Bonzini wrote:
>> On 4/28/23 17:01, Fabiano Rosas wrote:
>> > Also make sure our plugins support parallelism and report it properly
>> > to sphinx. Particularly, implement the merge_domaindata method in
>> > DBusDomain that is used to merge in data from other subprocesses.
>> >
>> > before:
>> > $ time make man html
>> > ...
>> > [1/2] Generating docs/QEMU manual with a custom command
>> > [2/2] Generating docs/QEMU man pages with a custom command
>> >
>> > real 0m43.157s
>> > user 0m42.642s
>> > sys 0m0.576s
>> >
>> > after:
>> > $ time make man html
>> > ...
>> > [1/2] Generating docs/QEMU manual with a custom command
>> > [2/2] Generating docs/QEMU man pages with a custom command
>> >
>> > real 0m25.014s
>> > user 0m51.288s
>> > sys 0m2.085s
>>
>> The 'nproc' fallback will potentially cause twice #CPUs processes to be
>> active, since sphinx will run in parallel with everything else.
>>
>> Is this result with "-j auto", and if so with which computer? If the
>> speedup is only 2x as it seems to be from the "time" above, I'd rather have
>> "-j 2" only so that sphinx doesn't risk killing the machine...
Tested with -j auto and -j16 on my 16 cpu i7-11850H.
>
> Why would it kill the machine ? If there are two sphinx processes
> concurrent, thus overcomitting available CPUs, the scheduler will
> just end up giving them shorter timeslice OS.
One other thing I noticed is that we're not actually running the two
documentation targets in parallel. The man pages have a dependency on
the html pages. I'm not sure if that is legitimate.
sphinxmans += custom_target('QEMU man pages',
build_by_default: build_docs,
output: these_man_pages,
HERE --> input: this_manual,
install: build_docs,
install_dir: install_dirs,
command: [SPHINX_ARGS, '-b', 'man', '-d',
private_dir,
input_dir, meson.current_build_dir()])
Removing that line gains us about 10 more seconds. However there are
some annoying differences in the man pages produced such as quotation
marks using a different character. I'm still investigating.
