Re: [PATCH 2.6.24-rc8-mm1 00/15] IPC: code rewrite + new functionalities

From: Benjamin Thery
Date: Mon Feb 04 2008 - 10:44:39 EST


Pavel Machek wrote:
Hi!

* Patches 9 to 15 propose to add some functionalities, and thus are
submitted here for RFC, about both the interest and their implementation.
These functionalities are:
- Two new control-commands:
. IPC_SETID: to change an IPC's id.
. IPC_SETALL: behaves as IPC_SET, except that it also sets all time
and pid values)
- add a /proc/<pid>/semundo file to read and write the undo values of
some semaphores for a given process.

As the namespaces and the "containers" are being integrated in the
kernel, these functionalities may be a first step to implement the
checkpoint/restart of an application: in fact the existing API does not allow
to specify or to change an ID when creating an IPC, when restarting an
application, and the times/pids values of each IPCs are also altered. May be
someone may find another interest about this ?

So again, comments are welcome.

Checkpoint/restart is nice, but... sysV ipc is broken by design, do we
really want to extend it?
Pavel

For my personal culture, what do you mean by "broken by design"?

Even if it's broken, don't you think some people could be interested in checkpointing "legacy" applications that use SysV IPC?

Benjamin

--
B e n j a m i n T h e r y - BULL/DT/Open Software R&D

http://www.bull.com
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