lkml.org 
[lkml]   [2006]   [Feb]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: (pspace,pid) vs true pid virtualization
    >> However, if we're going to get anywhere, the first decision which we
    >> need to make is whether to go with a (container,pid), (pspace,pid) or
    >> equivalent pair like approach, or a virtualized pid approach. Linus had
    >> previously said that he prefers the former. Since there has been much
    >> discussion since then, I thought I'd try to recap the pros and cons of
    >> each approach, with the hope that the head Penguins will chime in one
    >> more time, after which we can hopefully focus our efforts.
    I think the first thing we have to do, is not to decide which pids we
    want to see, but what and how we want to virtualize.

    > I am thinking that you can have both. Not in the sense of
    > overcomplicating, but in the sense of having your cake and eating it
    > too.
    BTW, really, why not both?
    Eric, can we do something universal which will suite all the parties?

    > The only thing which is a unique, system wide identifier for the process
    > is the &task_struct. So we are already virtualising this pointer into a
    > PID for userland. The only difference is that we cache it (nay, keep
    > the authorative version of it) in the task_struct.
    >
    > The (XID, PID) approach internally is also fine. This says that there
    > is a container XID, and within it, the PID refers to a particular
    > task_struct. A given task_struct will likely exist in more than one
    > place in the (XID, PID) space. Perhaps the values of PID for XID = 0
    > and XID = task.xid can be cached in the task_struct, but that is a
    > detail.
    >
    > Depending on the flags on the XID, we can incorporate all the approaches
    > being tabled. You want virtualised pids? Well, that'll hurt a little,
    > but suit yourself - set a flag on your container and inside the
    > container you get virtualised PIDs. You want a flat view for all your
    > vservers? Fine, just use an XID without the virtualisation flag and
    > with the "all seeing eye" property set. Or you use an XID _with_ the
    > virtualisation flag set, and then call a tuple-endowed API to find the
    > information you're after.
    This sounds good. But pspaces are also used for access controls. So this
    should be incorparated there as well.

    Kirill


    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2006-02-20 10:28    [W:6.097 / U:0.020 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site