The patch enable environment variable `BENCH_CMD` introduced in
a previous commit. The `taskset` alone will pin all the process
threads into a single (random) isolated CPU, there's a ticket [1]
about this in the Linux kernel bugtracker. The workaround is using
realtime scheduler for the isolated task using `chrt` [2], e. g.:
`taskset 0xef chrt 50`.

1. https://bugzilla.kernel.org/show_bug.cgi?id=116701
2. https://www.man7.org/linux/man-pages/man1/chrt.1.html

NO_CHANGELOG=performance testing
NO_DOC=performance testing
NO_TEST=performance testing