Re: [RFC][PATCH 2/7] VPIDs: pid/vpid conversions

From: Kirill Korotaev
Date: Tue Feb 21 2006 - 11:16:04 EST


The only correct thing you noticed is get_xpid on alpha. But this is
in fact a simple bug and half a year before we didn't care much for
archs others than i386/x86-64/ia64. That's it.
sidenote on that, maybe the various archs could
switch to C implementations of those 'special'
get_xpid() and friends, as I do not think they
are a) done that often (might be wrong there)
and b) recent gcc should get that right now anyway
I also wonder why it was required and can't be done in normal way...
Maybe worth trying to switch to C, really.

For example, networking is coupled with sysctl, which in turn are
coupled with proc filesystem. And sysfs! You even added a piece of code
in net/core/net-sysfs.c in your patch, which is a dirty hack.
Another example, mqueues and other subsystems which use netlinks and also depend on network context.
shmem/IPC is dependand on file system context and so on.
So it won't work when one have networking from one container and proc
from another.
the question should be: which part of proc should be part
of the pid space and which not, definitely the network
stuff would _not_ be part of the pid space ...
Ok, just one simple question:
how do you propose to handle network sysctls and network statistics/information in proc?
_how_ can you imagine this namespaces should work?
I see no elegant solution for this, do you? If there is any, I will be happy with namespaces again.

So I really see no much reasons to have separate namespaces, but it is ok for me if someone really wants it this way.
the reasons are, as I explained several times, that folks
use 'virtualization' or 'isolation' for many different
things, just because SWsoft only uses it for VPS doesn't
meant that it cannot be used for other things
Out of curiosity, do you have any _working_ examples of other usages?
I see only theoretical examples from you, but would like to hear from anyone who _uses_/_knows_ how to use it.

just consider isolating/virtualizing the network stack,
but leaving the processes in the same pid space, how to
do that in a sane way with a single reference?
I see... Any idea why this can be required?
(without proc? :) )
BTW, if you have virtualized networking, but not isolated fs namespace in this case, how are you going to handle unix sockets? Or maybe it's another separate namespace?

1. ask Linus about the preffered approach. I prepared an email for him
with a description of approaches.
why do you propose, if you already did? :)
because, the question was quite simple, isn't it?

2. start from networking/netfilters/IPC which are essentially the same
in both projects and help each other.
no problem with that, once Eric got there ...

Kirill


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