From: Thomas Gleixner <tglx@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>, bigeasy@linutronix.de
Cc: mark.rutland@arm.com, maz@kernel.org, catalin.marinas@arm.com,
will@kernel.org, chenhuacai@kernel.org, kernel@xen0n.name,
hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com,
borntraeger@linux.ibm.com, svens@linux.ibm.com,
pbonzini@redhat.com, wanpengli@tencent.com, vkuznets@redhat.com,
mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
x86@kernel.org, hpa@zytor.com, jgross@suse.com,
boris.ostrovsky@oracle.com, daniel.lezcano@linaro.org,
kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org,
decui@microsoft.com, rafael@kernel.org, peterz@infradead.org,
longman@redhat.com, boqun.feng@gmail.com, pmladek@suse.com,
senozhatsky@chromium.org, rostedt@goodmis.org,
john.ogness@linutronix.de, juri.lelli@redhat.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
bsegall@google.com, mgorman@suse.de, bristot@redhat.com,
vschneid@redhat.com, jstultz@google.com, sboyd@kernel.org,
linux-kernel@vger.kernel.org, loongarch@lists.linux.dev,
linux-s390@vger.kernel.org, kvm@vger.kernel.org,
linux-hyperv@vger.kernel.org, linux-pm@vger.kernel.org
Subject: Re: [PATCH v2 08/13] x86/vdso: Fix gettimeofday masking
Date: Thu, 01 Jun 2023 00:46:20 +0200 [thread overview]
Message-ID: <87y1l4dsqr.ffs@tglx> (raw)
In-Reply-To: <87r0qwfrm0.ffs@tglx>
On Wed, May 31 2023 at 17:27, Thomas Gleixner wrote:
> On Fri, May 19 2023 at 12:21, Peter Zijlstra wrote:
>> to take wrapping into account, but per all the above, we don't
>> actually wrap on u64 anymore.
>
> Indeed. The rationale was that you need ~146 years uptime with a 4GHz
> TSC or ~584 years with 1GHz to actually reach the wrap around point.
>
> Though I can see your point to make sure that silly BIOSes or VMMs
> cannot cause havoc by accident or malice.
>
> Did anyone ever validate that wrap around on TSC including TSC deadline
> timer works correctly?
>
> I have faint memories of TSC_ADJUST, which I prefer not to bring back to
> main memory :)
It seems my fears have been unjustified.
At least a quick test which sets the TSC to ~ -8min @2.1Ghz the machine
seems to survive without the colourful explosions I expected due to my
early exposure to TSC_ADJUST and TSC_DEADLINE_TIMER :)
Thanks,
tglx
next prev parent reply other threads:[~2023-05-31 22:46 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-19 10:20 [PATCH v2 00/13] local_clock() vs noinstr Peter Zijlstra
2023-05-19 10:20 ` [PATCH v2 01/13] seqlock/latch: Provide raw_read_seqcount_latch_retry() Peter Zijlstra
2023-06-05 19:16 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2023-05-19 10:21 ` [PATCH v2 02/13] time/sched_clock: Provide sched_clock_noinstr() Peter Zijlstra
2023-06-05 19:16 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2023-05-19 10:21 ` [PATCH v2 03/13] arm64/io: Always inline all of __raw_{read,write}[bwlq]() Peter Zijlstra
2023-05-24 16:40 ` Valentin Schneider
2023-06-05 19:16 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2023-05-19 10:21 ` [PATCH v2 04/13] arm64/arch_timer: Provide noinstr sched_clock_read() functions Peter Zijlstra
2023-05-24 16:40 ` Valentin Schneider
2023-06-02 11:54 ` Peter Zijlstra
2023-06-07 8:58 ` Valentin Schneider
2023-06-05 19:16 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2023-06-06 8:06 ` Peter Zijlstra
2023-06-06 8:13 ` Mark Rutland
2023-06-09 7:55 ` [tip: sched/core] arm64/arch_timer: Fix MMIO byteswap tip-bot2 for Peter Zijlstra
2023-05-19 10:21 ` [PATCH v2 05/13] loongarch: Provide noinstr sched_clock_read() Peter Zijlstra
2023-06-05 19:16 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2023-05-19 10:21 ` [PATCH v2 06/13] s390/time: Provide sched_clock_noinstr() Peter Zijlstra
2023-05-22 14:18 ` Heiko Carstens
2023-06-05 19:16 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2023-05-19 10:21 ` [PATCH v2 07/13] math64: Always inline u128 version of mul_u64_u64_shr() Peter Zijlstra
2023-06-05 19:16 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2023-05-19 10:21 ` [PATCH v2 08/13] x86/vdso: Fix gettimeofday masking Peter Zijlstra
2023-05-31 15:27 ` Thomas Gleixner
2023-05-31 22:46 ` Thomas Gleixner [this message]
2023-05-31 22:46 ` Thomas Gleixner
2023-06-05 19:16 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2023-05-19 10:21 ` [PATCH v2 09/13] clocksource: hyper-v: Adjust hv_read_tsc_page_tsc() to avoid special casing U64_MAX Peter Zijlstra
2023-05-19 18:38 ` Michael Kelley (LINUX)
2023-06-05 19:16 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2023-05-19 10:21 ` [PATCH v2 10/13] clocksource: hyper-v: Provide noinstr sched_clock() Peter Zijlstra
2023-06-05 19:16 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2023-05-19 10:21 ` [PATCH v2 11/13] x86/tsc: Provide sched_clock_noinstr() Peter Zijlstra
2023-06-05 19:16 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2023-05-19 10:21 ` [PATCH v2 12/13] sched/clock: Provide local_clock_noinstr() Peter Zijlstra
2023-06-05 19:16 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2023-05-19 10:21 ` [PATCH v2 13/13] cpuidle: Use local_clock_noinstr() Peter Zijlstra
2023-05-19 14:13 ` Rafael J. Wysocki
2023-06-05 19:16 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2023-05-19 18:48 ` [PATCH v2 00/13] local_clock() vs noinstr Michael Kelley (LINUX)
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