[RFC PATCH 0/8] Meson build system

[Silvan Jegen]

Hi

On Wed, Nov 30, 2016 at 11:00 AM, Daniel Stone <daniel at fooishbar.org> wrote:
> Hey Emil,
> Thanks for the detailed reply! :) It's really interesting to hear your
> perspective, especially with Mesa also using SCons.
>
> On 30 November 2016 at 01:02, Emil Velikov <emil.l.velikov at gmail.com> wrote:
>> On 29 November 2016 at 20:50, Daniel Stone <daniel at fooishbar.org> wrote:
>>>> As you know better than me the actual speed increase isn't in using
>>>> Meson, it's due to ninja.
>>>>
>>>> If one is to use (write?) make backend for Meson the results wouldn't
>>>> be that different.
>>>
>>> I disagree. Using Ninja is nice, and a huge win, but there is already
>>> a massive, massive, massive, win before you invoke either Make or
>>> Ninja; just generating the configuration (autoreconf + ./configure vs.
>>> meson) is 16.75 seconds on my laptop (again, current-generation Intel
>>> with 16GB of RAM) for autotools, vs. 1.24 seconds for Meson. If
>>> they're equal, we'd have 53.96s vs. 28.0sec for the total build,
>>> rather than 53.96 vs. 12.47.
>>>
>> Thanks for the reminder how much configure sucks and how much faster
>> non-recursive makefiles are.
>
> Heh, Wayland and Weston both (apart from docs) use non-recursive
> Makefiles! We took the readability hit of flattening everything into
> one Makefile so we could get a speed/parallelism boost.
>
>> Numbers seems far better over here...
>>
>> $ git clean -fXd -- .. && rm -rf * && time (../autogen.sh
>> --prefix=/tmp/wayland-autotools --disable-documentation)
>> ~10 real
>>
>> The rest of the number also seems to vary noticeably, despite having a
>> lower spec machine.
>> Using stock Arch here, should distro of choice matter that much ?
>>
>> System 3 ('Laptop'): Dell XPS 13 9350, 2.5GHz dual-core Intel Skylake
>> i7-6500U, 4MB cache, 16GB RAM, storage on NVME/PCI-E, make -j8
>>
>> System X ('Laptop 2'): Lenovo X1C3, 245GHz dual-core Intel Broadwell
>> i7-5500U, 4MB cache, 8GB RAM, storage on NVME/PCI-E, make -j8
>>
>>
>> NB: Everything but the Install test, varies ±0.2s across 3 consecutive
>> runs, thus it's been rounded to the closest 0.5s on average.
>>
>>          |          Laptop |       Laptop 2 |
>> ---------+-----------------+----------------+
>> Full     | 27.78s / 11.24s |   ~21s /  ~10s |
>> Rebuild  | 13.80s /  9.63s | ~12.5s / ~8.5s |
>> Check    | 13.22s /  8.80s |  ~7.5s / ~5.5s |
>> Install  |  0.47s /  0.14s |  0.47s / 0.14s |
>> ---------+-----------------+----------------+
>
> Ha, this isn't Skylake laptop vs. Broadwell laptop, this is my 14-core
> Xeon vs. your Broadwell laptop! That they're so different suggests
> that our configuration is pretty wildly different - are you perhaps
> not building a load of stuff which configure autodetects? That's the
> only way I can imagine how your laptop would outpace a £4000
> workstation. :\

I wonder how much of the difference is due to the speed of the
NVME/PCI-E SSD Emil is using.

In my limited experience, the Xeons on my server did not perform as
well as the (higher tacted) i5 CPU on my desktop for some simple XML
processing task (provided the degree of parallelism is the same of
course).


Cheers,

Silvan