From nobody Sun May 30 12:52:16 2021 X-Original-To: bugs@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 76C70C7AAE4 for ; Sun, 30 May 2021 12:52:16 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4FtJGm2tgfz4j7v for ; Sun, 30 May 2021 12:52:16 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2610:1c1:1:606c::50:1d]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 4C34F1D4DC for ; Sun, 30 May 2021 12:52:16 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.5]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id 14UCqG4K085074 for ; Sun, 30 May 2021 12:52:16 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id 14UCqGfJ085073 for bugs@FreeBSD.org; Sun, 30 May 2021 12:52:16 GMT (envelope-from bugzilla-noreply@freebsd.org) X-Authentication-Warning: kenobi.freebsd.org: www set sender to bugzilla-noreply@freebsd.org using -f From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 256261] TSC-low hardware timer breaks C-States on Intel Core2 generation of CPUs Date: Sun, 30 May 2021 12:52:16 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: 13.0-STABLE X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Many People X-Bugzilla-Who: freebsd@frost.kiwi X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: bugs@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version rep_platform op_sys bug_status bug_severity priority component assigned_to reporter Message-ID: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated List-Id: Bug reports List-Archive: https://lists.freebsd.org/archives/freebsd-bugs List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-bugs@freebsd.org MIME-Version: 1.0 X-ThisMailContainsUnwantedMimeParts: N https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D256261 Bug ID: 256261 Summary: TSC-low hardware timer breaks C-States on Intel Core2 generation of CPUs Product: Base System Version: 13.0-STABLE Hardware: amd64 OS: Any Status: New Severity: Affects Many People Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: freebsd@frost.kiwi FreeBSD users with an Intel Core2 CPU have reported broken C-states for a w= hile now, as originally reported here: https://forums.freebsd.org/threads/c-states-not-used.66192/ The CPU would refuse to enter any C-state higher than C1. As a result power consumption suffered. Luckily this is a known issue in DragonFlyBSD, with hardware timers being at fault ( https://www.dragonflybsd.org/docs/user/Powersave/#index1h2 ). The fix for FreeBSD is simpler: Simply changing the hardware time to anythi= ng other than TSC-low fixes the issue and the CPU enters C2 and higher. Eg. kern.timecounter.hardware=3DHPET=20 A quick workaround would be to disable the TSC-low timer on all Intel Core2 CPUs, by lowering it's timecounter.choise score. --=20 You are receiving this mail because: You are the assignee for the bug.=