Re: [PATCH x86_64] Live Patching Function on

From: Andi Kleen
Date: Tue Apr 26 2005 - 08:08:43 EST

On Tue, Apr 26, 2005 at 10:34:56AM +0900, Takashi Ikebe wrote:
> I think that's the common sense in every carrier.
> If we reboot the switch, the service will be disrupted.
> The phone network is lifeline, and does not allow to be disrupt by just
> bug fix.
> I think same kind of function is needed in many real
> enterprise/mission-critical/business area.
> All do with ptrace may affect target process's time critical task. (need
> to stop target process whenever fix)

Sorry, but what are your exact time requirements for this?

Remember any x86-64 CPU is really fast and it can do a _lot_ of ptrace
operations in a very short time.

Just a vague "it may be too slow" is not enough justification to
push a lot of redundant code into the kernel. Also if ptrace
should be really too slow (which I doubt, but you are welcome
to show some numbers together with real time requirements from
a real system) then we could optimize ptrace for this, e.g.
by adding a ptrace subcommand to copy whole memory blocks
more efficiently or maybe even do a mmap like thing.

But unless someone actually demonstrates this is needed it seems far overkill.

> All implement in user application costs too much, need to implement all
> the application...(and I do not know this approach really works on time
> critical applications yet.)

I think you have a lot of unproved and doubtful assumptions here.

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