On 2022/10/25 2:48, ISHIKAWA,chiaki wrote:
Build System and Mach Environment
*
Starting with Bug 1746462
<https://bugzilla.mozilla.org/show_bug.cgi?id=1746462>you can use
the mold linker for linking Mozilla Firefox on most Linux
distributions. MacOS support will come shortly.
I tested "mold" for building C-C thunderbird.
I was impressed.
|The I/O speed during linking "libxul", the large libary, is near the
max bandwidth of my local disk setup (on a linux guest within
VirtualBox hosted under Windows 10).
I watched the xosview's disk I/O activity with amusement.
As is described in Bugzilla, then all of a sudden the multiple CPU's
got busy (I have assigned 7 vCPUs to my linux guest and 16GB of memory
assigned) and linking was over.
In contrast, with GNU gold which I have been using, I see prolonged
I/O not near the maximum bandwidth and single CPU getting busy during
long linking.
Of course, the linking is only a small portion of the whole build
process, but it *IS* a lengthy process.
This is a great work.
Keep the good work going!
Chiaki
I think this has a large impact on tryserver.
Before, I have noticed that typical build has a very long tail end of
single CPU usage. This was the long linking process, I think.
I mentioned once on one of the mailing list (or bugzilla?) that the link
ought to get started as early as possible to avoid this.
It seems it was started rather early after all, but slow linking showed
this behavior.
However, with mold, the link process actually ends rather early and such
a tail end of single CPU usage is not visible at all now.
In my local setup where I monitor the compilation through emacs shell
buffer, the verbose output of housechore commands (it seems build was
creating jar files under various directories)
is printed for like several seconds very quickly at the end (very light
CPU consumption way after the burst of heavy parallel usage is gone) and
the build ends then.
I have never seen such end behavior of build before. It used to be a
very long link process at the end and these housechore commands ended
well before link ended.
I believe someone ought to check the job workload profile in the
tryserver once mold becomes widely used.
It can possibly ends the jobs quicker, or the parallel CPU usage and
large memory footprint may impact the farm negatively.
It all depends on the workload profile. In my single build environment,
mold performs very well to my pleasant surprise.
I wonder if it will be available under Windows (!?).
THAT will change the CPU/IO workload of tryserver computer farm.
Chiaki
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