From: Suleiman Souhlal <ssouhlal@FreeBSD.org>
To: Shem Multinymous <multinymous@gmail.com>
Cc: Andi Kleen <ak@suse.de>,
Linux Kernel ML <linux-kernel@vger.kernel.org>,
vojtech@suse.cz, Jiri Bohac <jbohac@suse.cz>,
Nigel Cunningham <ncunningham@cyclades.com>,
Pavel Machek <pavel@suse.cz>
Subject: Re: [PATCH 0/2] Make the TSC safe to be used by gettimeofday().
Date: Tue, 14 Nov 2006 09:06:09 -0800 [thread overview]
Message-ID: <4559F781.6020607@FreeBSD.org> (raw)
In-Reply-To: <41840b750611140430k3b46023dr9a01b8b38bbb535d@mail.gmail.com>
Shem Multinymous wrote:
> On 11/14/06, Suleiman Souhlal <ssouhlal@freebsd.org> wrote:
>
>> I believe that the results returned will always be monotonic, as long as
>> the frequency of the TSC does not change from under us (that is, without
>> the kernel knowing). This is because we "synchronize" each CPU's vxtime
>> with a global time source (HPET) every time we know the TSC rate changes.
>
>
> Does this hold after a suspend/resume cycle? You could be resuming
> with a different CPU clock than what you suspended with, and I'm not
> sure anything guarantees an early enough re-sync.
I have to admit that I didn't really design this patch with
suspend/resume in mind, and that I'm not too familiar with how they work.
Do the HPET/ACPI timers still run while the system is suspended?
If not, there shouldn't be any problem, as long as the kernel is
informed of the resume early enough.
-- Suleiman
next prev parent reply other threads:[~2006-11-14 17:06 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-11-14 1:06 [PATCH 0/2] Make the TSC safe to be used by gettimeofday() Suleiman Souhlal
2006-11-14 1:08 ` [PATCH 1/2] " Suleiman Souhlal
2006-11-14 2:05 ` Andi Kleen
2006-11-14 2:25 ` Suleiman Souhlal
2006-11-14 2:44 ` Andi Kleen
2006-11-14 3:35 ` dean gaudet
2006-11-14 4:22 ` dean gaudet
2006-11-14 3:54 ` Suleiman Souhlal
2006-11-14 11:12 ` Andi Kleen
2006-11-14 1:09 ` [PATCH 2/2] Introduce a vmonotonic_clock() vsyscall Suleiman Souhlal
2006-11-14 1:50 ` [PATCH 0/2] Make the TSC safe to be used by gettimeofday() Andi Kleen
2006-11-14 2:06 ` Suleiman Souhlal
2006-11-14 11:10 ` [PATCH 0/2] Make the TSC safe to be used by gettimeofday() II Andi Kleen
2006-11-14 12:30 ` [PATCH 0/2] Make the TSC safe to be used by gettimeofday() Shem Multinymous
2006-11-14 17:06 ` Suleiman Souhlal [this message]
2006-11-14 18:30 ` Andi Kleen
2006-11-14 21:28 ` Christoph Lameter
2006-11-14 7:42 ` Arjan van de Ven
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