[cgl_discussion] Re: [cgl_specs] Use case - Live patching

Takashi Ikebe ikebe.takashi at lab.ntt.co.jp
Tue Mar 29 00:47:32 PST 2005


Ralf,
As steve said, live patch is intended to use for carrier specific 
applications. We do not intend to apply distro's mature applications.
So I'll fix use-case document so.

Basically, there is some condition for applying live patch to process 
safely, such as function size, software structure.
So it is very hard to apply live patch to applications which does not 
pay attention to live patch.(So I think nobody apply live patch to 
distro applications without distro-provided fix modules for live patch.)

 > I am wondering why the distro then should even provide that 
functionality?
 > Why doesn't the app provider take care of this himself then if it is just
 > meant for his app?
In my *personal* opinion, common function makes software development 
cost lower, and performance good.
Well you can make the live patching function to each application.
However there is many carrier specific applications(not few!) on system.
Therefore it is not efficient to implement the function to all 
application from cost and performance point of view.(From performance 
point of view, If each APL need to implement the function, each APL need 
to check the live patch request at any stoppable point, it makes 
performance worse... )
 From performance(Real time) point of view, we think the function should 
be implemented in kernel.(Our requirement of allowed process stopping 
time is few milliseconds)



Ralf Flaxa wrote:
> Then it should be stated very explicitely that this feature may only
> be used for and by applications and that it is forbidden to patch
> the underlying distro with it.
> 
> I am wondering why the distro then should even provide that functionality?
> Why doesn't the app provider take care of this himself then if it is just
> meant for his app?
> 
> 	Ralf
> 
> On Mon, Mar 28, 2005 at 03:19:07PM -0700, Steven Dake wrote:
> 
>>>From the distro perspective, I can understand your serious discomfort
>>with supporting live patching of applications specific to the operating
>>system (and in the distributor's support domain).
>>
>>The live patching feature, atleast during the specs development, was
>>targetd for use in carrier(and other interested parties) applications
>>which are supported and maintained by the carriers/others.  We  never
>>stated in the requirements that the distribution itself must support
>>live patching of the entire system.  If you point out the specific
>>requirement that requires or implies this, then it is something that
>>needs adjustment in the specification..
>>
>>Perhaps wording of the intended use (for carrier applications, not for
>>distro upgrades) would be helpful.
>>
>>If live patching then becomes a "customer issue", it is really of no
>>concern to a distro whether the customer chooses to patch their own
>>applications or not.
>>
>>Regards
>>-steve


-- 
Takashi Ikebe
NTT Network Service Systems Laboratories
9-11, Midori-Cho 3-Chome Musashino-Shi,
Tokyo 180-8585 Japan
Tel : +81 422 59 4246, Fax : +81 422 60 4012
e-mail : ikebe.takashi at lab.ntt.co.jp



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