Re: [ANNOUNCE] udev 0.1 release

Steven Dake
2003-04-11T22:23:33Z

Arnd Bergmann wrote:

>Greg KH wrote:
>
>
>
>>On Fri, Apr 11, 2003 at 01:29:57PM -0700, Steven Dake wrote:
>>
>>
>>>It gets even worse, because performance of hotswap events on disk adds
>>>is critical and spawning processes is incredibly slow compared to the
>>>performance required by some telecom applications...
>>>
>>>
>>It's critical that we quick name this disk within X milliseconds after
>>it has been added to the system? What spec declares this?
>>
>>
>
>While the problem might not really be the per-device latency, what should
>be handled correctly is the following scenario:
>
>- Someone accidentally removes the cable that connects a few hundred
> (mounted) disks
>- The cable is replaced, but - oops - to the wrong socket
>- The person notices the error and now places the cable into the right
> socket.
>
>At this time we have four concurrent hotplug events for every single
>disks that we want to be finished in order and we want every disk
>to end up with its original minor number in the end. If this is not
>possible, the system still needs to be in a sensible state after this.
>
>
Yes, and in the rest of my email, I stated this would be solved by
replacing /sbin/hotplug with a mechanism to communicate events to a user
space daemon which would process requests in order as submitted by the
kernel. (All except the same minor/major, which may or may not happen).
If the kernel is evil and doesn't submit events in order, thats another
problem to solve, but it should for disk events, atleast.

> Arnd <><
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