From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161974AbdEYAtj (ORCPT ); Wed, 24 May 2017 20:49:39 -0400 Received: from mga02.intel.com ([134.134.136.20]:53220 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1034024AbdEYAte (ORCPT ); Wed, 24 May 2017 20:49:34 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.38,389,1491289200"; d="scan'208";a="91476022" Subject: Re: [tip:x86/debug] x86/timers: Add simple udelay calibration To: Jan Kiszka , brgerst@gmail.com, mathias.nyman@linux.intel.com, dvlasenk@redhat.com, tglx@linutronix.de, peterz@infradead.org, bp@alien8.de, luto@kernel.org, torvalds@linux-foundation.org, hpa@zytor.com, jpoimboe@redhat.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, mingo@kernel.org, linux-tip-commits@vger.kernel.org References: <1490083293-3792-2-git-send-email-baolu.lu@linux.intel.com> <225381e1-5ad6-7208-697d-73cbb56163cc@siemens.com> From: Lu Baolu Message-ID: <59262A15.4080402@linux.intel.com> Date: Thu, 25 May 2017 08:49:25 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <225381e1-5ad6-7208-697d-73cbb56163cc@siemens.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 05/25/2017 12:56 AM, Jan Kiszka wrote: > On 2017-03-21 13:19, tip-bot for Lu Baolu wrote: >> Commit-ID: dd759d93f4dd4fd2f345a78ad1223bb3edf3ee7b >> Gitweb: http://git.kernel.org/tip/dd759d93f4dd4fd2f345a78ad1223bb3edf3ee7b >> Author: Lu Baolu >> AuthorDate: Tue, 21 Mar 2017 16:01:29 +0800 >> Committer: Ingo Molnar >> CommitDate: Tue, 21 Mar 2017 12:28:45 +0100 >> >> x86/timers: Add simple udelay calibration >> >> Add a simple udelay calibration in x86 architecture-specific >> boot-time initializations. This will get a workable estimate >> for loops_per_jiffy. Hence, udelay() could be used after this >> initialization. >> >> Signed-off-by: Lu Baolu >> Acked-by: Thomas Gleixner >> Cc: Andy Lutomirski >> Cc: Borislav Petkov >> Cc: Brian Gerst >> Cc: Denys Vlasenko >> Cc: Greg Kroah-Hartman >> Cc: H. Peter Anvin >> Cc: Josh Poimboeuf >> Cc: Linus Torvalds >> Cc: Mathias Nyman >> Cc: Peter Zijlstra >> Cc: linux-usb@vger.kernel.org >> Link: http://lkml.kernel.org/r/1490083293-3792-2-git-send-email-baolu.lu@linux.intel.com >> Signed-off-by: Ingo Molnar >> --- >> arch/x86/kernel/setup.c | 22 ++++++++++++++++++++++ >> 1 file changed, 22 insertions(+) >> >> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c >> index 4bf0c89..e70204e 100644 >> --- a/arch/x86/kernel/setup.c >> +++ b/arch/x86/kernel/setup.c >> @@ -837,6 +837,26 @@ dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p) >> return 0; >> } >> >> +static void __init simple_udelay_calibration(void) >> +{ >> + unsigned int tsc_khz, cpu_khz; >> + unsigned long lpj; >> + >> + if (!boot_cpu_has(X86_FEATURE_TSC)) >> + return; >> + >> + cpu_khz = x86_platform.calibrate_cpu(); >> + tsc_khz = x86_platform.calibrate_tsc(); >> + >> + tsc_khz = tsc_khz ? : cpu_khz; >> + if (!tsc_khz) >> + return; >> + >> + lpj = tsc_khz * 1000; >> + do_div(lpj, HZ); >> + loops_per_jiffy = lpj; >> +} >> + >> /* >> * Determine if we were loaded by an EFI loader. If so, then we have also been >> * passed the efi memmap, systab, etc., so we should use these data structures >> @@ -985,6 +1005,8 @@ void __init setup_arch(char **cmdline_p) >> */ >> x86_configure_nx(); >> >> + simple_udelay_calibration(); >> + >> parse_early_param(); >> >> #ifdef CONFIG_MEMORY_HOTPLUG >> > Can we move this past init_hypervisor_platform()? Yes, we can as far as I can see. Best regards, Lu Baolu > Otherwise, the > x86_platform hooks aren't fully initialized yet, and we may use the > wrong functions. > > Jan >