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From: Thomas Gleixner <tglx@linutronix.de>
To: Huacai Chen <chenhc@lemote.com>
Cc: Andy Lutomirski <luto@kernel.org>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	LKML <linux-kernel@vger.kernel.org>,
	stable <stable@vger.kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	Paul Burton <paul.burton@mips.com>,
	"open list:MIPS" <linux-mips@vger.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 110/110] lib/vdso: Improve do_hres() and update vdso data unconditionally
Date: Wed, 23 Oct 2019 10:48:11 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.21.1910231037500.2308@nanos.tec.linutronix.de> (raw)
In-Reply-To: <CAAhV-H4PEcCgOBL8ksjc+4LC9VPoCRBMtuGEK6ckmdJYXjdcSg@mail.gmail.com>

On Tue, 22 Oct 2019, Huacai Chen wrote:

  https://people.kernel.org/tglx/notes-about-netiquette

Look for Toppost
 
> If we use (s64)cycles < 0, then how to solve the problem that a 64bit
> counter become negative?

I doubt that you will be able to observe that. A 64bit value becomes
negative after 1<<63 cycles, i.e. at 1GHz thats 292 years of uptime.

What's your problem?

Thanks,

	tglx

WARNING: multiple messages have this Message-ID (diff)
From: Thomas Gleixner <tglx@linutronix.de>
To: Huacai Chen <chenhc@lemote.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
	LKML <linux-kernel@vger.kernel.org>,
	stable <stable@vger.kernel.org>,
	"open list:MIPS" <linux-mips@vger.kernel.org>,
	Paul Burton <paul.burton@mips.com>,
	Andy Lutomirski <luto@kernel.org>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 110/110] lib/vdso: Improve do_hres() and update vdso data unconditionally
Date: Wed, 23 Oct 2019 10:48:11 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.21.1910231037500.2308@nanos.tec.linutronix.de> (raw)
In-Reply-To: <CAAhV-H4PEcCgOBL8ksjc+4LC9VPoCRBMtuGEK6ckmdJYXjdcSg@mail.gmail.com>

On Tue, 22 Oct 2019, Huacai Chen wrote:

  https://people.kernel.org/tglx/notes-about-netiquette

Look for Toppost
 
> If we use (s64)cycles < 0, then how to solve the problem that a 64bit
> counter become negative?

I doubt that you will be able to observe that. A 64bit value becomes
negative after 1<<63 cycles, i.e. at 1GHz thats 292 years of uptime.

What's your problem?

Thanks,

	tglx

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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2019-10-23  8:48 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-21 12:52 [PATCH 110/110] lib/vdso: Improve do_hres() and update vdso data unconditionally Huacai Chen
2019-10-21 12:52 ` Huacai Chen
2019-10-21 14:52 ` Thomas Gleixner
2019-10-21 14:52   ` Thomas Gleixner
2019-10-21 14:58   ` Thomas Gleixner
2019-10-21 14:58     ` Thomas Gleixner
2019-10-22  2:42     ` Huacai Chen
2019-10-22  2:42       ` Huacai Chen
2019-10-23  8:48       ` Thomas Gleixner [this message]
2019-10-23  8:48         ` Thomas Gleixner

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