On Friday, 19 January 2018 13:29:51 GMT Rich Freeman wrote: > On Fri, Jan 19, 2018 at 12:26 AM, victor romanchuk <r...@persimplex.net> wrote: > > local:jumbo-build:www-client/chromium: Combine source files to speed up > > build process.> > > setting that significantly speeds up emerge time (tried it twice; the > > second attempt had the flag set) > > > > $ qlop -gHv -d `date +%Y-%m-%d` chromium > > chromium-63.0.3239.132: Fri Jan 19 03:15:43 2018: 1 hour, 47 minutes, 28 > > seconds chromium-63.0.3239.132: Fri Jan 19 06:11:06 2018: 1 hour, 16 > > minutes, 14 seconds chromium: 2 times > > There is a CPU-memory tradeoff here. Combining source files reduces > duplication of #include directives which greatly cuts down on the > number of lines of code going into the compiler, but the individual > files being compiled are larger. > > I have a 12 SMT-core Ryzen 5-1600, and 16GB of RAM. I can't even > build chromium on a tmpfs because the RAM+space requirements have > grown, so I build on an SSD. Even without the tmpfs I have to reduce > make to -j11 or it will OOM during a build WITHOUT the jumbo-build > flag. So, I'm already hitting RAM limitations on build time. > > That said, I've experimented with some build times and I found that I > can build chromium faster with -j8 using jumbo-build (the max # jobs I > can run reliably without OOM) than I can build it with -j11 without > using the new feature. I'll also note that to do this I have to make > sure nothing else is compiling at the same time, and sometimes I end > up stopping a container that runs mono for good measure. > > I do use ccache in general with chromium but I did my benchmarking without > it. > > I suggest experimenting with jumbo-build, and consider reducing > parallel jobs if you run into OOM, but depending on your system you > might find it not worth the trouble. > > One thing I haven't experimented with is reducing -j even further and > then moving back to a tmpfs. I could easily see a tmpfs for building > outperforming jumbo-build even if I end up at -j4 or less. Then > again, the SSD probably isn't as bad a drag as a spinning disk would > be. > > I was chatting with somebody (I think on reddit) who mentioned > jumbo-build worked fine on a threadripper with 64GB of RAM (that would > be -j32 I suppose). I bet that with even a few more GB of RAM I could > probably max out my 12 SMT cores. > > I can't wait to see how chromium-64 behaves. The RAM requirements > have been steadily going up. I have an older system with only 4GB RAM > and it struggles to even build chromium at all.
On my old i7 laptop it eats up all 4G of RAM and 4G of swap before it conks out. So, I dropped the jobs to 3 and --load-average to 2, added a swapfile to increase disk space and it now builds in around 13 hours. I have not used jumbo-build, but perhaps I should? -- Regards, Mick
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