From owner-svn-src-all@freebsd.org Thu Mar 21 03:20:22 2019 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 29914154AAB4; Thu, 21 Mar 2019 03:20:22 +0000 (UTC) (envelope-from freebsd@gndrsh.dnsmgr.net) Received: from gndrsh.dnsmgr.net (br1.CN84in.dnsmgr.net [69.59.192.140]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id E7DB069E42; Thu, 21 Mar 2019 03:20:20 +0000 (UTC) (envelope-from freebsd@gndrsh.dnsmgr.net) Received: from gndrsh.dnsmgr.net (localhost [127.0.0.1]) by gndrsh.dnsmgr.net (8.13.3/8.13.3) with ESMTP id x2L3KIDD058580; Wed, 20 Mar 2019 20:20:18 -0700 (PDT) (envelope-from freebsd@gndrsh.dnsmgr.net) Received: (from freebsd@localhost) by gndrsh.dnsmgr.net (8.13.3/8.13.3/Submit) id x2L3KIjc058579; Wed, 20 Mar 2019 20:20:18 -0700 (PDT) (envelope-from freebsd) From: "Rodney W. Grimes" Message-Id: <201903210320.x2L3KIjc058579@gndrsh.dnsmgr.net> Subject: Re: svn commit: r345359 - in head/sys/cddl/dev/dtrace: amd64 i386 In-Reply-To: <201903210252.x2L2qMSP022374@repo.freebsd.org> To: Mark Johnston Date: Wed, 20 Mar 2019 20:20:18 -0700 (PDT) CC: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Reply-To: rgrimes@freebsd.org X-Mailer: ELM [version 2.4ME+ PL121h (25)] MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII X-Rspamd-Queue-Id: E7DB069E42 X-Spamd-Bar: ++ Authentication-Results: mx1.freebsd.org X-Spamd-Result: default: False [2.28 / 15.00]; ARC_NA(0.00)[]; HAS_REPLYTO(0.00)[rgrimes@freebsd.org]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[4]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_GOOD(-0.10)[text/plain]; RCVD_TLS_LAST(0.00)[]; DMARC_NA(0.00)[dnsmgr.net]; AUTH_NA(1.00)[]; REPLYTO_DOM_NEQ_FROM_DOM(0.00)[]; RCVD_COUNT_THREE(0.00)[3]; IP_SCORE(0.02)[ip: (0.08), ipnet: 69.59.192.0/19(0.04), asn: 13868(0.02), country: US(-0.07)]; NEURAL_SPAM_SHORT(0.31)[0.313,0]; MX_GOOD(-0.01)[cached: gndrsh.dnsmgr.net]; NEURAL_SPAM_LONG(0.38)[0.377,0]; NEURAL_SPAM_MEDIUM(0.69)[0.686,0]; R_SPF_NA(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:13868, ipnet:69.59.192.0/19, country:US]; MID_RHS_MATCH_FROM(0.00)[] X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 21 Mar 2019 03:20:22 -0000 > Author: markj > Date: Thu Mar 21 02:52:22 2019 > New Revision: 345359 > URL: https://svnweb.freebsd.org/changeset/base/345359 > > Log: > Don't attempt to measure TSC skew when running as a VM guest. > > It simply doesn't work in general since VCPUs may migrate between > physical cores. The approach used to measure skew also doesn't > make much sense in a VM. "May" is the important aspect here, and to my knowledge both bhyve and Vmware provide a way to pin cpus there should be a way for us to turn this back on if it is desired. Sticking it under the big knob vm_guest is probably not the most flexiable solution. Could we please have someway to force this back on? > > PR: 218452 > MFC after: 2 weeks > Sponsored by: The FreeBSD Foundation > > Modified: > head/sys/cddl/dev/dtrace/amd64/dtrace_subr.c > head/sys/cddl/dev/dtrace/i386/dtrace_subr.c > > Modified: head/sys/cddl/dev/dtrace/amd64/dtrace_subr.c > ============================================================================== > --- head/sys/cddl/dev/dtrace/amd64/dtrace_subr.c Thu Mar 21 01:16:37 2019 (r345358) > +++ head/sys/cddl/dev/dtrace/amd64/dtrace_subr.c Thu Mar 21 02:52:22 2019 (r345359) > @@ -319,6 +319,9 @@ dtrace_gethrtime_init(void *arg) > int i; > #endif > > + if (vm_guest) > + return; > + > /* The current CPU is the reference one. */ > sched_pin(); > tsc_skew[curcpu] = 0; > > Modified: head/sys/cddl/dev/dtrace/i386/dtrace_subr.c > ============================================================================== > --- head/sys/cddl/dev/dtrace/i386/dtrace_subr.c Thu Mar 21 01:16:37 2019 (r345358) > +++ head/sys/cddl/dev/dtrace/i386/dtrace_subr.c Thu Mar 21 02:52:22 2019 (r345359) > @@ -321,6 +321,9 @@ dtrace_gethrtime_init(void *arg) > int i; > #endif > > + if (vm_guest) > + return; > + > /* The current CPU is the reference one. */ > sched_pin(); > tsc_skew[curcpu] = 0; > > -- Rod Grimes rgrimes@freebsd.org