Date: Mon, 9 Dec 2019 21:27:01 -0500 From: Ryan Stone <rysto32@gmail.com> To: FreeBSD Current <freebsd-current@freebsd.org> Subject: dtrace not working on bhyve VM without invariant_tsc Message-ID: <CAFMmRNz9Cv2Hepi%2BszMn30BBGKEyEcvUQiE-46kEdpxg6rjH9w@mail.gmail.com>
next in thread | raw e-mail | index | archive | help
I have a bhyve VM guest on my laptop where dtrace just constantly aborts whenever I try to use it: [rstone@ebpf dtrace]sudo dtrace -s fdcopy.d Assertion failed: (buf->dtbd_timestamp >= first_timestamp), file /usr/home/rstone/git/bsd-worktree/ebpf-import/cddl/contrib/opensolaris/lib/libdtrace/common/dt_consume.c, line 3026. Abort trap I believe that the problem is caused by dtrace unconditionally using rdtsc() to implement dtrace_gethrtime(), assuming that the values will be stable for a given CPU. The VM's vcpus seem to be getting migrated frequently. Should dtrace instead be using the system timecounter? That should stand a much better chance of being monotonically increasing.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CAFMmRNz9Cv2Hepi%2BszMn30BBGKEyEcvUQiE-46kEdpxg6rjH9w>