Re: + prctl-add-pr_setget_child_reaper-to-allow-simple-process-supervision.patch added to -mm tree

[Linus Torvalds]

On Thu, Aug 18, 2011 at 2:55 PM, Kay Sievers <kay.sievers@xxxxxxxx> wrote:
>
>> So NAK. We're not slowing down normal code for some new feature that
>> realistically will never be used by any normal applications.
>
> It will be used for all new service managers. UNIX is a pain if you want
> to watch your children regarding double-forking, if you are not init.

I'll believe that "all new service managers" when I see it. Until
then, a new feature is just that - a new feature. Which nobody uses.

> And it will clean up the mess the desktop stuff is putting in 'ps afx'.
> Here is the before/after output:
>
>  253 ?        Ss     0:00 /bin/dbus-daemon --system --address=systemd: --nofork --systemd-activation
>  294 ?        Sl     0:00 /usr/libexec/polkit-1/polkitd
>  328 ?        S      0:00 /usr/sbin/modem-manager
>  608 ?        Sl     0:00 /usr/libexec/colord
>  658 ?        Sl     0:00 /usr/libexec/upowerd
>  819 ?        Sl     0:00 /usr/libexec/imsettings-daemon
>  916 ?        Sl     0:00 /usr/libexec/udisks-daemon
>  917 ?        S      0:00  \_ udisks-daemon: not polling any devices
>
>
>  294 ?        Ss     0:00 /bin/dbus-daemon --system --address=systemd: --nofork --systemd-activation
>  426 ?        Sl     0:00  \_ /usr/libexec/polkit-1/polkitd
>  449 ?        S      0:00  \_ /usr/sbin/modem-manager
>  635 ?        Sl     0:00  \_ /usr/libexec/colord
>  705 ?        Sl     0:00  \_ /usr/libexec/upowerd
>  959 ?        Sl     0:00  \_ /usr/libexec/udisks-daemon
>  960 ?        S      0:00  |   \_ udisks-daemon: not polling any devices
>  977 ?        Sl     0:00  \_ /usr/libexec/packagekitd

Yeah, that looks like a nice feature.

> If you want, we can make the forked processes inherit a flag if the
> 'subreaper' should be looked up at all. Then we have almost zero
> overhead if the feature isn't used. You think that's needed?

Yes, I do. Because with any current system, that "almost zero
overhead" is just totally wasted effort entirely for zero gain. Which
just makes me go "Eww".

             Linus
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