From: Thomas Gleixner <tglx@linutronix.de>
To: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: steven.sistare@oracle.com, daniel.m.jordan@oracle.com,
linux@armlinux.org.uk, schwidefsky@de.ibm.com,
heiko.carstens@de.ibm.com, john.stultz@linaro.org,
sboyd@codeaurora.org, x86@kernel.org,
linux-kernel@vger.kernel.org, mingo@redhat.com, hpa@zytor.com,
douly.fnst@cn.fujitsu.com, peterz@infradead.org,
prarit@redhat.com, feng.tang@intel.com, pmladek@suse.com,
gnomes@lxorguk.ukuu.org.uk, linux-s390@vger.kernel.org
Subject: Re: [PATCH v12 03/11] x86/tsc: redefine notsc to behave as tsc=unstable
Date: Sat, 23 Jun 2018 15:32:36 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.21.1806231532200.8650@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20180621212518.19914-4-pasha.tatashin@oracle.com>
On Thu, 21 Jun 2018, Pavel Tatashin wrote:
> Currently, notsc kernel parameter disables the use of tsc register by
> sched_clock(). However, this parameter does not prevent linux from
> accessing tsc in other places in kernel.
>
> The only rational to boot with notsc is to avoid timing discrepancies on
> multi-socket systems where different tsc frequencies may present, and thus
> fallback to jiffies for clock source.
>
> However, there is another method to solve the above problem, it is to boot
> with tsc=unstable parameter. This parameter allows sched_clock() to use tsc
> but in case tsc is outside of expected interval it is corrected back to a
> sane value.
>
> This is why there is no reason to keep notsc, and it can be removed. But,
> for compatibility reasons we will keep this parameter but change its
> definition to be the same as tsc=unstable.
>
> Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
> Reviewed-by: Dou Liyang <douly.fnst@cn.fujitsu.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
next prev parent reply other threads:[~2018-06-23 13:51 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-21 21:25 [PATCH v12 00/11] Early boot time stamps for x86 Pavel Tatashin
2018-06-21 21:25 ` [PATCH v12 01/11] x86: text_poke() may access uninitialized struct pages Pavel Tatashin
2018-06-21 21:37 ` Randy Dunlap
2018-06-25 8:14 ` Peter Zijlstra
2018-06-25 8:39 ` Thomas Gleixner
2018-06-25 9:09 ` Peter Zijlstra
2018-06-25 9:18 ` Thomas Gleixner
2018-06-25 9:22 ` Peter Zijlstra
2018-06-25 12:32 ` Pavel Tatashin
2018-06-25 13:48 ` Peter Zijlstra
2018-06-25 14:06 ` Pavel Tatashin
2018-06-21 21:25 ` [PATCH v12 02/11] x86: initialize static branching early Pavel Tatashin
2018-06-23 9:16 ` Borislav Petkov
2018-06-23 13:11 ` Pavel Tatashin
2018-06-21 21:25 ` [PATCH v12 03/11] x86/tsc: redefine notsc to behave as tsc=unstable Pavel Tatashin
2018-06-23 13:32 ` Thomas Gleixner [this message]
2018-06-21 21:25 ` [PATCH v12 04/11] kvm/x86: remove kvm memblock dependency Pavel Tatashin
2018-06-23 13:36 ` Thomas Gleixner
2018-07-05 16:12 ` Paolo Bonzini
2018-07-06 9:24 ` Thomas Gleixner
2018-07-06 9:36 ` Paolo Bonzini
2018-07-06 9:45 ` Thomas Gleixner
2018-07-06 10:08 ` Paolo Bonzini
2018-07-06 10:44 ` Thomas Gleixner
2018-07-06 10:50 ` Thomas Gleixner
2018-07-06 15:03 ` Pavel Tatashin
2018-07-06 15:09 ` Paolo Bonzini
2018-06-21 21:25 ` [PATCH v12 05/11] s390/time: add read_persistent_wall_and_boot_offset() Pavel Tatashin
2018-06-25 7:07 ` Martin Schwidefsky
2018-06-25 12:45 ` Pavel Tatashin
2018-06-21 21:25 ` [PATCH v12 06/11] time: replace read_boot_clock64() with read_persistent_wall_and_boot_offset() Pavel Tatashin
2018-06-23 13:49 ` Thomas Gleixner
2018-06-21 21:25 ` [PATCH v12 07/11] s390/time: remove read_boot_clock64() Pavel Tatashin
2018-06-21 21:25 ` [PATCH v12 08/11] ARM/time: " Pavel Tatashin
2018-06-23 13:52 ` Thomas Gleixner
2018-06-21 21:25 ` [PATCH v12 09/11] x86/tsc: prepare for early sched_clock Pavel Tatashin
2018-06-23 16:50 ` Thomas Gleixner
2018-06-23 18:49 ` Pavel Tatashin
2018-06-23 20:11 ` Thomas Gleixner
2018-06-23 21:29 ` Pavel Tatashin
2018-06-23 23:38 ` Thomas Gleixner
2018-06-24 2:43 ` Pavel Tatashin
2018-06-24 7:30 ` Thomas Gleixner
2018-06-26 15:42 ` Thomas Gleixner
2018-06-26 18:42 ` Pavel Tatashin
2018-06-26 19:47 ` Pavel Tatashin
2018-06-28 7:31 ` Thomas Gleixner
2018-06-28 10:43 ` Thomas Gleixner
2018-06-28 11:46 ` Peter Zijlstra
2018-06-28 12:27 ` Thomas Gleixner
2018-06-28 19:42 ` Pavel Tatashin
2018-06-29 7:30 ` Thomas Gleixner
2018-06-29 8:57 ` Pavel Tatashin
2018-07-03 20:59 ` Thomas Gleixner
2018-07-02 17:18 ` Konrad Rzeszutek Wilk
2018-06-29 14:30 ` Andy Shevchenko
2018-06-29 17:50 ` Andy Shevchenko
2018-07-09 23:16 ` Boris Ostrovsky
2018-06-21 21:25 ` [PATCH v12 10/11] sched: early boot clock Pavel Tatashin
2018-06-25 8:55 ` Peter Zijlstra
2018-06-25 12:44 ` Pavel Tatashin
2018-06-25 19:23 ` Pavel Tatashin
2018-06-26 9:00 ` Peter Zijlstra
2018-06-26 11:27 ` Pavel Tatashin
2018-06-26 11:51 ` Pavel Tatashin
2018-06-26 15:07 ` Peter Zijlstra
2018-06-21 21:25 ` [PATCH v12 11/11] x86/tsc: use tsc early Pavel Tatashin
2018-06-23 16:56 ` Thomas Gleixner
2018-06-23 21:38 ` Pavel Tatashin
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