From owner-freebsd-current@freebsd.org Tue Dec 10 02:27:19 2019 Return-Path: Delivered-To: freebsd-current@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id A9C611CBDD6 for ; Tue, 10 Dec 2019 02:27:19 +0000 (UTC) (envelope-from rysto32@gmail.com) Received: from mail-qv1-xf2a.google.com (mail-qv1-xf2a.google.com [IPv6:2607:f8b0:4864:20::f2a]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "GTS CA 1O1" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 47X3qV4yWZz4JQD for ; Tue, 10 Dec 2019 02:27:18 +0000 (UTC) (envelope-from rysto32@gmail.com) Received: by mail-qv1-xf2a.google.com with SMTP id p2so3550352qvo.10 for ; Mon, 09 Dec 2019 18:27:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to; bh=hzpEWkugOVyQ9CkiNaD0GcS0w12eVyPWnsx7zB3+UoM=; b=B5uGGzjHmBtcqFAc2mm+yeVwNI4IO8NIe6QDv+vbVBe8ZCzddLV57oXkxEWV6ANYVo ZelLvb9XA1XSO8rkzKCKOOjU4qil330bM2FHiR+KqDxNhW9UYQ+RuTFmo6rRcUdbbC8/ 4+I1RZ781jR3xfGrnUBZ/cZ75gUmWicN7ll2jiNlgBbSC14ShunushZXlCWYKYvvv/dR q0kMbTJDO6I/3sczkAZRXCYT6ndibsQHuYtIKVeRAH7X3g8dmF0xzSNCEIul059123NG IuT9uPJ3a4gNay8jMZEPuul4rJiKcXw4DlCK9TiDgGe12j5GImglJLU9mql2rBMS+Xs2 +LaQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=hzpEWkugOVyQ9CkiNaD0GcS0w12eVyPWnsx7zB3+UoM=; b=MVw4EmVSw9jqA0vigQv0xnhwfEi+wETvYr71mF6ARWoxBmrihhYw9LSheFviXC9GHd L52V37b8xnQiwwOhQ32sVu51vuUWqPB7Lxo9bVcC1HgZl/kkpxAtJzKQBvRAmFSz4FQT WFpp82w+bDxkslzqAjxwfbFCis9EIwIIOVsj5s0yxjVHlwYPOdJ0SwzNrxa00D2I3nUn I6LkncOBiMUzlL1AjjYB3F2M+53MAs/SizL0CczRHQkZfK34zsAirnrKYPmSlaGVGmV2 nooVyqluUG2tlXJmseLMzybnWMoH+un3s1Vf+jtc7n62Vfg9ixvCt0XpPax62KB2o33g rR1g== X-Gm-Message-State: APjAAAVGth1Ze9XnN3lLPOqlsijgJMZsp5IQ3yc3EGQcS2uBMETeCyAs 0+vhGW63M0Pk7Y5lebRbwEmFzWtGgc5zZVqq0s24MkKO X-Google-Smtp-Source: APXvYqzc/IUGLun+tjkPM2fwFQGb7incFkcOrml0FsJOkIunwfz26FqvldZz5ST/69t2tSxZMrGOUNimSp/ZqQq7X3Q= X-Received: by 2002:a05:6214:13a8:: with SMTP id h8mr25694182qvz.41.1575944831888; Mon, 09 Dec 2019 18:27:11 -0800 (PST) MIME-Version: 1.0 From: Ryan Stone Date: Mon, 9 Dec 2019 21:27:01 -0500 Message-ID: Subject: dtrace not working on bhyve VM without invariant_tsc To: FreeBSD Current Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 47X3qV4yWZz4JQD X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20161025 header.b=B5uGGzjH; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (mx1.freebsd.org: domain of rysto32@gmail.com designates 2607:f8b0:4864:20::f2a as permitted sender) smtp.mailfrom=rysto32@gmail.com X-Spamd-Result: default: False [-3.00 / 15.00]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20161025]; FROM_HAS_DN(0.00)[]; R_SPF_ALLOW(-0.20)[+ip6:2607:f8b0:4000::/36]; FREEMAIL_FROM(0.00)[gmail.com]; MIME_GOOD(-0.10)[text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-current@freebsd.org]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; IP_SCORE_FREEMAIL(0.00)[]; RCPT_COUNT_ONE(0.00)[1]; IP_SCORE(0.00)[ipnet: 2607:f8b0::/32(-2.22), asn: 15169(-1.92), country: US(-0.05)]; TO_DN_ALL(0.00)[]; DKIM_TRACE(0.00)[gmail.com:+]; DMARC_POLICY_ALLOW(-0.50)[gmail.com,none]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; FREEMAIL_ENVFROM(0.00)[gmail.com]; ASN(0.00)[asn:15169, ipnet:2607:f8b0::/32, country:US]; RCVD_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[]; DWL_DNSWL_NONE(0.00)[gmail.com.dwl.dnswl.org : 127.0.5.0] X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 10 Dec 2019 02:27:19 -0000 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.