From: john stultz <johnstul@us.ibm.com>
To: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Daniel Walker <dwalker@mvista.com>, Ingo Molnar <mingo@elte.hu>,
mbligh@google.com, linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [RFC] Fast assurate clock readable from user space and NMI handler
Date: Tue, 27 Feb 2007 11:40:24 -0800 [thread overview]
Message-ID: <1172605224.15970.43.camel@localhost> (raw)
In-Reply-To: <20070227190442.GA11272@Krystal>
On Tue, 2007-02-27 at 14:04 -0500, Mathieu Desnoyers wrote:
> __get_nsec_offset : reads clock->cycle_last. Should be called with
> xtime_lock held. (ok so far, but see below)
>
> change_clocksource
> clock->cycle_last = now; (non atomic 64 bits update. Not protected by
> any lock ?) -> this would race with __get_nsec_offset ?
Minor nit (it could probably use a comment fixup): its only called from
update_wall_time, which holds xtime_lock.
> update_wall_time
> Called from timer interrupt. Holds xtime_lock and has a priority higher
> than other interrupts. Other clock->cycle_last protected by
> write_seqlock_irqsave.
-john
next prev parent reply other threads:[~2007-02-27 19:41 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-11-24 21:59 [PATCH 8/16] LTTng 0.6.36 for 2.6.18 : Timestamp Mathieu Desnoyers
[not found] ` <1164475747.5196.5.camel@localhost.localdomain>
[not found] ` <20061126170542.GA30771@Krystal>
[not found] ` <1164561427.16871.14.camel@localhost.localdomain>
[not found] ` <20061126231833.GA22241@Krystal>
[not found] ` <1164585589.16871.52.camel@localhost.localdomain>
2007-02-24 16:19 ` [RFC] Fast assurate clock readable from user space and NMI handler Mathieu Desnoyers
2007-02-24 18:06 ` Daniel Walker
2007-02-26 20:53 ` Mathieu Desnoyers
2007-02-26 21:27 ` Daniel Walker
2007-02-26 22:14 ` Mathieu Desnoyers
2007-02-26 23:12 ` Daniel Walker
2007-02-27 3:54 ` Mathieu Desnoyers
2007-02-27 4:22 ` Daniel Walker
2007-02-27 4:47 ` Mathieu Desnoyers
2007-02-27 6:29 ` Ingo Molnar
2007-02-27 7:38 ` Mathieu Desnoyers
2007-02-27 8:48 ` Thomas Gleixner
2007-02-27 10:18 ` Daniel Walker
2007-02-27 16:02 ` Mathieu Desnoyers
2007-02-27 17:24 ` Daniel Walker
2007-02-27 19:04 ` Mathieu Desnoyers
2007-02-27 19:40 ` john stultz [this message]
2007-02-27 20:09 ` Daniel Walker
2007-02-27 9:59 ` Daniel Walker
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