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From: Jeff Dike <jdike@addtoit.com>
To: john stultz <johnstul@us.ibm.com>
Cc: linux-kernel@vger.kernel.org,
	user-mode-linux-devel@lists.sourceforge.net
Subject: Re: [uml-devel] Re: [RFC] PATCH 0/4 - Time virtualization
Date: Thu, 13 Apr 2006 21:53:16 -0400	[thread overview]
Message-ID: <20060414015316.GA7723@ccure.user-mode-linux.org> (raw)
In-Reply-To: <1144974688.8548.26.camel@cog.beaverton.ibm.com>

On Thu, Apr 13, 2006 at 05:31:27PM -0700, john stultz wrote:
> Looks interesting. I've never quite understood the need for different
> time domains, it only allows you to run one domain with the incorrect
> time, but I'm sure there is some use case that is desired.

There are a few possible answers -

If when this virtualization stuff is done, no one has done anything with
time, someone is going to moan.

Once in a while, you want to fiddle your system clock to make sure that
a cron job or something does what it's supposed to.

There was some extra infrastructure that UML needed in order to start using
this stuff, so I chose a fairly simple virtualization case to accompany it.

> I'm not psyched about possible namespace vs nanosecond confusion w/
> terms like "time_ns", but that's pretty minor.

Yeah, names can be changed.

> Also I hope you're not wanting to deal w/ NTP adjustments between
> domains that have the incorrect time? That would be very ugly.

No, the domain stores an offset from the system time, so it automatically
gets the system's NTP adjustments.

				Jeff

WARNING: multiple messages have this Message-ID (diff)
From: Jeff Dike <jdike@addtoit.com>
To: john stultz <johnstul@us.ibm.com>
Cc: linux-kernel@vger.kernel.org,
	user-mode-linux-devel@lists.sourceforge.net
Subject: Re: [uml-devel] Re: [RFC] PATCH 0/4 - Time virtualization
Date: Thu, 13 Apr 2006 21:53:16 -0400	[thread overview]
Message-ID: <20060414015316.GA7723@ccure.user-mode-linux.org> (raw)
In-Reply-To: <1144974688.8548.26.camel@cog.beaverton.ibm.com>

On Thu, Apr 13, 2006 at 05:31:27PM -0700, john stultz wrote:
> Looks interesting. I've never quite understood the need for different
> time domains, it only allows you to run one domain with the incorrect
> time, but I'm sure there is some use case that is desired.

There are a few possible answers -

If when this virtualization stuff is done, no one has done anything with
time, someone is going to moan.

Once in a while, you want to fiddle your system clock to make sure that
a cron job or something does what it's supposed to.

There was some extra infrastructure that UML needed in order to start using
this stuff, so I chose a fairly simple virtualization case to accompany it.

> I'm not psyched about possible namespace vs nanosecond confusion w/
> terms like "time_ns", but that's pretty minor.

Yeah, names can be changed.

> Also I hope you're not wanting to deal w/ NTP adjustments between
> domains that have the incorrect time? That would be very ugly.

No, the domain stores an offset from the system time, so it automatically
gets the system's NTP adjustments.

				Jeff


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  reply	other threads:[~2006-04-14  2:52 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-04-13 17:19 [RFC] PATCH 0/4 - Time virtualization Jeff Dike
2006-04-13 17:19 ` [uml-devel] " Jeff Dike
2006-04-14  0:31 ` john stultz
2006-04-14  0:31   ` [uml-devel] " john stultz
2006-04-14  1:53   ` Jeff Dike [this message]
2006-04-14  1:53     ` Jeff Dike
2006-04-14 16:24     ` john stultz
2006-04-14 16:24       ` john stultz
2006-04-19  8:25 ` Eric W. Biederman
2006-04-19  8:25   ` [uml-devel] " Eric W. Biederman
2006-04-26 18:01   ` Jeff Dike
2006-04-26 18:01     ` [uml-devel] " Jeff Dike
2006-04-28 11:33     ` Blaisorblade
2006-04-28 11:33       ` Blaisorblade
2006-04-28 11:48       ` Jeff Dike
2006-04-28 11:48         ` Jeff Dike
2006-04-28 12:14         ` Jeff Dike
2006-04-28 12:14           ` Jeff Dike
2006-04-28 13:54         ` Blaisorblade
2006-04-28 13:54           ` Blaisorblade
2006-04-28 15:15           ` Jeff Dike
2006-04-28 15:15             ` Jeff Dike
2006-04-28 20:10             ` Blaisorblade
2006-04-28 20:10               ` Blaisorblade
2006-04-28 16:18           ` Eric W. Biederman
2006-04-28 16:18             ` Eric W. Biederman
2006-04-14 15:39 Brock, Anthony - NET
2006-04-14 15:33 ` Jeff Dike

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