From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751728AbcGNPXI (ORCPT ); Thu, 14 Jul 2016 11:23:08 -0400 Received: from mail-wm0-f65.google.com ([74.125.82.65]:33067 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751455AbcGNPXE (ORCPT ); Thu, 14 Jul 2016 11:23:04 -0400 From: Nicolai Stange To: Thomas Gleixner Cc: Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Borislav Petkov , Paolo Bonzini , Viresh Kumar , Hidehiro Kawai , "Peter Zijlstra (Intel)" , "Christopher S. Hall" , Adrian Hunter , linux-kernel@vger.kernel.org, Nicolai Stange Subject: [PATCH v4 0/2] reduce TSC deadline frequency errors Date: Thu, 14 Jul 2016 17:22:53 +0200 Message-Id: <20160714152255.18295-1-nicstange@gmail.com> X-Mailer: git-send-email 2.9.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The v3 series can be found at http://lkml.kernel.org/g/20160713130344.8319-1-nicstange@gmail.com Applicable to linux-next-20160708 (in case you wonder why I turned back from the 20160712 given in v3 to 20160708 again: mysteriously, 20160712 doesn't boot neither w/ nor w/o this series anymore). The individual patches don't depend on each other. Changes to v3: As Paolo Bonzini pointed out in reply to v3, for the values of 2, 4 and 8 of TSC_DIVISOR, the 64 bit division (u32)(((u64)tsc_khz * 1000) / TSC_DIVISOR) can be safely turned into a 32 bit division by changing associativity: tsc_khz * (1000 / TSC_DIVISOR) In doing so, it suggests itself to squash former [1/3] ("arch, x86, tsc deadline clockevent dev: reduce frequency roundoff error") and [2/3] ("arch, x86, tsc deadline clockevent dev: reduce TSC_DIVISOR to 2") into a single patch. Furthermore, reducing TSC_DIVISOR down to 2 becomes unnessecary -- setting it to 8 suffices already. Thus, - [1/2] ("arch, x86, tsc deadline clockevent dev: eliminate frequency roundoff error") Former [1/3] and [2/3] squashed together. Don't reduce TSC_DIVISOR to 2 but to 8 only. Change associativity in order to get rid of the 64 bit division. Adapt the commit message accordingly. - [2/2] ("arch, x86, tsc: inform TSC deadline clockevent device about recalibration") Former [3/3]. Likewise change associativity in order to get rid of the 64 bit division here, too. Changes to v2: - [3/3] ("arch, x86, tsc: inform TSC deadline clockevent device about recalibration") Use clockevents_update_freq() rather than clockevents_config(). - Former [4/4] ("kernel/time/clockevents: compensate for monotonic clock's dynamic frequency") Split off, not a member of this series anymore. Changes to v1: - [1/3] ("arch, x86, tsc deadline clockevent dev: reduce frequency roundoff error") No changes to the patch. Note that the v1 mail could not be delivered to the author of the TSC_DIVISOR introducing commit 279f1461432c ("x86: apic: Use tsc deadline for oneshot when available"), Suresh Siddha , so I had to remove him from the CC list. - [2/3] ("arch, x86, tsc deadline clockevent dev: reduce TSC_DIVISOR to 2") Likewise. - [3/3] ("arch, x86, tsc: inform TSC deadline clockevent device about recalibration") Silence the kbuild test robot on ARCH=i386 by wrapping the new call to lapic_update_tsc_freq() from arch/x86/kernel/tsc.c in an #ifdef CONFIG_X86_LOCAL_APIC. Nicolai Stange (2): arch, x86, tsc deadline clockevent dev: eliminate frequency roundoff error arch, x86, tsc: inform TSC deadline clockevent device about recalibration arch/x86/include/asm/apic.h | 1 + arch/x86/kernel/apic/apic.c | 28 ++++++++++++++++++++++++++-- arch/x86/kernel/tsc.c | 6 ++++++ 3 files changed, 33 insertions(+), 2 deletions(-) -- 2.9.0