mk(1) says to set NPROC in the environment, INSTALL does that itself, but only on foreign platforms.
Now I see cascades of 'clang -DPLAN9PORT ...' procs in top(1). OK? Index: Makefile =================================================================== RCS file: /cvs/ports/plan9/plan9port/Makefile,v retrieving revision 1.41 diff -u -p -r1.41 Makefile --- Makefile 31 Jan 2023 10:26:17 -0000 1.41 +++ Makefile 11 May 2023 14:22:26 -0000 @@ -35,7 +35,7 @@ pre-configure: bin/macedit do-build: - cd ${WRKSRC} && env CC9="${CC}" CCFLAGS="${CFLAGS}" ./INSTALL -b + cd ${WRKSRC} && env CC9="${CC}" CCFLAGS="${CFLAGS}" NPROC=${MAKE_JOBS} ./INSTALL -b do-install: rm -f ${WRKSRC}/.travis.yml