Date: Mon, 6 Sep 2021 21:34:13 +0200 From: Wolfram Schneider <wosch@freebsd.org> To: David Chisnall <theraven@freebsd.org> Cc: freebsd-current@freebsd.org Subject: Re: -CURRENT compilation time Message-ID: <CAMWY7CCUXJmUT8g1irOUNAxgihhoqpcTcV1nF7MR1NHCVY-%2BEQ@mail.gmail.com> In-Reply-To: <b0dadbd1-3f99-ef8e-0a35-f35d3dab828c@FreeBSD.org> References: <CAGSa5y0FMwt8g4%2BmqFegvrgBzxJCwupB_RJqb52ZUQy9EFB__Q@mail.gmail.com> <b0dadbd1-3f99-ef8e-0a35-f35d3dab828c@FreeBSD.org>
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On Mon, 6 Sept 2021 at 11:44, David Chisnall <theraven@freebsd.org> wrote: > > On 06/09/2021 09:08, Jeremie Le Hen wrote: > > Compiling C++ seems > > extremely CPU heavy and this is made worse by the fact LLVM is built > > twice (once for build/cross tools, once for the actual world). > > Note that you need to build LLVM twice only if you are actively > debugging LLVM reproduceable deployment images. You actually don't need > to build it at all, you can use an external toolchain to skip the first > build and you can compile WITHOUT_TOOLCHAIN to avoid building the > version that's installed and then install a toolchain from packages: > > https://wiki.freebsd.org/ExternalToolchain I did a test on a 16 core (32 VCPU) machine (Intel(R) Xeon(R) CPU E5-2630 v3 @ 2.40GHz). With the option WITHOUT_TOOLCHAIN=yes the world build time is 2.5 times faster (real or user+sys), down from 48 min to 19.5 min real time. time make -j16 buildworld -------------------------------------------------------------- >>> World build completed on Mon Sep 6 12:00:45 UTC 2021 >>> World built in 2862 seconds, ncpu: 32, make -j16 -------------------------------------------------------------- 2862.04 real 41234.87 user 1582.66 sys time make -j16 WITHOUT_TOOLCHAIN=yes buildworld -------------------------------------------------------------- >>> World build completed on Mon Sep 6 11:32:41 UTC 2021 >>> World built in 1181 seconds, ncpu: 32, make -j16 -------------------------------------------------------------- 1180.73 real 16076.27 user 988.73 sys -Wolfram -- Wolfram Schneider <wosch@FreeBSD.org> https://wolfram.schneider.org
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