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-flto=jobserver does not use all CPU cores
- From: "R. Diez via gcc-help" <gcc-help at gcc dot gnu dot org>
- To: gcc-help <gcc-help at gcc dot gnu dot org>
- Date: Fri, 14 Feb 2020 08:19:35 +0100
- Subject: -flto=jobserver does not use all CPU cores
- References: <b1619349-e0f5-d06c-c23f-06c2b63520dd.ref@yahoo.de>
- Reply-to: "R. Diez" <rdiezmail-gcc at yahoo dot de>
Hi all:
I have an AMD FX-4300 Quad-Core Processor with no hyperthreading.
If I run GCC with -flto, only core is used, as expected.
If I run GCC with -flto=4, all 4 cores are used, as expected.
If I run GCC with -flto=jobserver, only 2 cores are apparently used, even if the top-level makefile runs with -j 40. The increased linking
time also corroborates this.
I am using a self-built GCC 8.3.0 cross-compiler for ARM Cortex-M4F on Ubuntu 18.04.4 LTS.
I am also using a self-built GNU Make 4.2.1. Everything else is building in parallel with all cores.
Is this problem with "-flto=jobserver" already known? I couldn't find anything on this.
How can I debug what is going on? Is there a way to trace jobserver-related information?
Thanks in advance,
rdiez