From owner-svn-src-all@freebsd.org Thu Mar 21 16:25:25 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 8B17D15473ED; Thu, 21 Mar 2019 16:25:25 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Received: from smtp.freebsd.org (smtp.freebsd.org [IPv6:2610:1c1:1:606c::24b:4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "smtp.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 27B816C061; Thu, 21 Mar 2019 16:25:25 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Received: from John-Baldwins-MacBook-Pro-3.local (ralph.baldwin.cx [66.234.199.215]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client did not present a certificate) (Authenticated sender: jhb) by smtp.freebsd.org (Postfix) with ESMTPSA id 7EF9E18CAE; Thu, 21 Mar 2019 16:25:24 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Subject: Re: svn commit: r345359 - in head/sys/cddl/dev/dtrace: amd64 i386 To: Mark Johnston , src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org References: <201903210252.x2L2qMSP022374@repo.freebsd.org> From: John Baldwin Openpgp: preference=signencrypt Autocrypt: addr=jhb@FreeBSD.org; keydata= mQGiBETQ+XcRBADMFybiq69u+fJRy/0wzqTNS8jFfWaBTs5/OfcV7wWezVmf9sgwn8TW0Dk0 c9MBl0pz+H01dA2ZSGZ5fXlmFIsee1WEzqeJzpiwd/pejPgSzXB9ijbLHZ2/E0jhGBcVy5Yo /Tw5+U/+laeYKu2xb0XPvM0zMNls1ah5OnP9a6Ql6wCgupaoMySb7DXm2LHD1Z9jTsHcAQMD /1jzh2BoHriy/Q2s4KzzjVp/mQO5DSm2z14BvbQRcXU48oAosHA1u3Wrov6LfPY+0U1tG47X 1BGfnQH+rNAaH0livoSBQ0IPI/8WfIW7ub4qV6HYwWKVqkDkqwcpmGNDbz3gfaDht6nsie5Z pcuCcul4M9CW7Md6zzyvktjnbz61BADGDCopfZC4of0Z3Ka0u8Wik6UJOuqShBt1WcFS8ya1 oB4rc4tXfSHyMF63aPUBMxHR5DXeH+EO2edoSwViDMqWk1jTnYza51rbGY+pebLQOVOxAY7k do5Ordl3wklBPMVEPWoZ61SdbcjhHVwaC5zfiskcxj5wwXd2E9qYlBqRg7QeSm9obiBCYWxk d2luIDxqaGJARnJlZUJTRC5vcmc+iGAEExECACAFAkTQ+awCGwMGCwkIBwMCBBUCCAMEFgID AQIeAQIXgAAKCRBy3lIGd+N/BI6RAJ9S97fvbME+3hxzE3JUyUZ6vTewDACdE1stFuSfqMvM jomvZdYxIYyTUpC5Ag0ERND5ghAIAPwsO0B7BL+bz8sLlLoQktGxXwXQfS5cInvL17Dsgnr3 1AKa94j9EnXQyPEj7u0d+LmEe6CGEGDh1OcGFTMVrof2ZzkSy4+FkZwMKJpTiqeaShMh+Goj XlwIMDxyADYvBIg3eN5YdFKaPQpfgSqhT+7El7w+wSZZD8pPQuLAnie5iz9C8iKy4/cMSOrH YUK/tO+Nhw8Jjlw94Ik0T80iEhI2t+XBVjwdfjbq3HrJ0ehqdBwukyeJRYKmbn298KOFQVHO EVbHA4rF/37jzaMadK43FgJ0SAhPPF5l4l89z5oPu0b/+5e2inA3b8J3iGZxywjM+Csq1tqz hltEc7Q+E08AAwUIAL+15XH8bPbjNJdVyg2CMl10JNW2wWg2Q6qdljeaRqeR6zFus7EZTwtX sNzs5bP8y51PSUDJbeiy2RNCNKWFMndM22TZnk3GNG45nQd4OwYK0RZVrikalmJY5Q6m7Z16 4yrZgIXFdKj2t8F+x613/SJW1lIr9/bDp4U9tw0V1g3l2dFtD3p3ZrQ3hpoDtoK70ioIAjjH aIXIAcm3FGZFXy503DOA0KaTWwvOVdYCFLm3zWuSOmrX/GsEc7ovasOWwjPn878qVjbUKWwx Q4QkF4OhUV9zPtf9tDSAZ3x7QSwoKbCoRCZ/xbyTUPyQ1VvNy/mYrBcYlzHodsaqUDjHuW+I SQQYEQIACQUCRND5ggIbDAAKCRBy3lIGd+N/BCO8AJ9j1dWVQWxw/YdTbEyrRKOY8YZNwwCf afMAg8QvmOWnHx3wl8WslCaXaE8= Message-ID: Date: Thu, 21 Mar 2019 09:25:20 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:60.0) Gecko/20100101 Thunderbird/60.5.3 MIME-Version: 1.0 In-Reply-To: <201903210252.x2L2qMSP022374@repo.freebsd.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 27B816C061 X-Spamd-Bar: ------ Authentication-Results: mx1.freebsd.org X-Spamd-Result: default: False [-6.95 / 15.00]; REPLY(-4.00)[]; NEURAL_HAM_SHORT(-0.95)[-0.953,0]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; NEURAL_HAM_LONG(-1.00)[-1.000,0] 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 16:25:25 -0000 On 3/20/19 7:52 PM, Mark Johnston wrote: > 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. > > 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; I do think I would prefer 'if (vm_guest != VM_GUEST_NO)' or some such vs 'if (vm_guest)'. The latter does read well, but it seems like comparisons against enums should always be against an enum value? That seems more consistent with our rule to require pointers to be compared with NULL for example. -- John Baldwin