On Sat, Jun 15, 2019, at 14:19, Walter Dnes wrote:
> On Thu, Jun 13, 2019 at 05:15:41PM +0300, Alexey Eschenko wrote
> > Thank you. Didn't think about that. Don't know why though. My
> > MAKEOPTS was "-j32". Looks like that was too many for package like
> > qtwebengine. Solved the problem with creating specific environment
> > for qtwebengine and setting it up in /etc/portage/package.env/ It was
> > veeeery long build process but this time it finished successfully. I
> > think I'll try to find more appropriate value for qtwebengine which
> > could be used with 32GB of RAM.
>
> Please use plain text, not HTML.
>
> According to
> https://blogs.gentoo.org/ago/2013/01/14/makeopts-jcore-1-is-not-the-best-optimization/
> the fastest compiles come with setting MAKEOPTS to the number of cores
> in your machine. E.g. for a dual core cpu, use "-j2", for a 4 core cpu
> use "-j4", etc. To check the number of cpus in your machine, execute...
>
> grep -c ^flags /proc/cpuinfo
That's a good rule but not necessarily always true. My old machine was an
i7-3930K (6 cores, 12 threads) w/ 32G RAM. I had /var/tmp on tmpfs. I
benchmarked firefox, chromium, and some other big projects once and -j13 was
consistently the fastest on that box.
As that blog post says:
> I’m just saying, ${core} + 1 is not the best optimization for me
> and the test confirms the part:“but this guideline isn’t always perfect”
Depends on available RAM, how fast your disk is, etc.
Alec
