Re: SCO: "thread creation is about a thousand times faster than on

From: Marco Colombo (marco@esi.it)
Date: Thu Aug 31 2000 - 15:10:29 EDT

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    On Tue, 29 Aug 2000, Pavel Machek wrote:

    > Hi!
    >
    [...]
    > > > So you need some hackery to make mount(8) cause change in all
    > > > namespaces at once. Whatever is done, this will be gross.
    > > > I suppose you'd require a loopback of some sort, so that one
    > > > might rip the real filesystem out from under /var/mail instead
    > > > of trying to unmount it in 50 different namespaces... ugh.
    > >
    > > Not. Loopback would be gross, but I'm not proposing it. OTOH, getting all
    > > mailreaders work with IMAP with _no_ changes in said mailreaders is a
    > > Good Thing(tm). So is free (for mailreaders) support of any weird
    > > protocol, format and location of mailbox, locking scheme, etc. - do it in
    > > one place and that's it. Everything looks like we have the mailbox in
    > > fixed format on local filesystem, no matter WTF is actually out there.
    > > And guess what? It doesn't have to be one process and it's nowhere near
    > > the kernel mode, or even suid.
    >
    > What does this have to do with private namespaces?
    >
    > mailfsd /dev/coda0 --enable-imap &
    > mount /dev/coda0 /var/spool/mail

    So every user will see /var/spool/mail. There must be a single mailfsd
    for all users.

    With private namespaces, every user can run his/her own mailfsd,
    privately mount /var/spool/mail, and run a mailer program to access
    one or more IMAP mailbox as /var/spool/mail/<mailbox>.

    But I must say I don't really get the difference in running my own
    mailfsd, mounting ~/mail and having the mailer program read IMAP
    mailboxes there (OK, /var/spool/mail/<user> is the default INBOX
    for many mailers, and some of them don't let you change that... but
    this is a minor issue, just recompile them).

    All I need is a private mount point (and privileges to mount on it).

    >
    > It looks easy to me, today and without private namespaces.
    > [Shall I hack podfuk into providing imap? Okay, it would not be easy
    > because
    > * /var/spool/mail/xxx is _writable_, so your imap dream is probably
    > dream. What does your mailfs do when someone does cat /bin/bash >
    > $MYMAIL
    > * podfuk is has file granularity
    >
    > I could see it working with some kind of directory format, however.]
    > Pavel
    > --
    > I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care."
    > Panos Katsaloulis describing me w.r.t. patents at discuss@linmodems.org
    > -
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    > Please read the FAQ at http://www.tux.org/lkml/
    >

    .TM.

    -- 
          ____/  ____/   /
         /      /       /			Marco Colombo
        ___/  ___  /   /		      Technical Manager
       /          /   /			 ESI s.r.l.
     _____/ _____/  _/		       Colombo@ESI.it
    

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