Messages in this thread | | | Date | Mon, 1 Dec 2014 15:33:38 +0300 | From | Pavel Emelyanov <> | Subject | Re: [RFC PATCH] proc, pidns: Add highpid |
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On 12/01/2014 09:47 AM, Florian Weimer wrote: > * Andy Lutomirski: > >> On Nov 30, 2014 1:47 AM, "Florian Weimer" <fw@deneb.enyo.de> wrote: >>> >>> * Andy Lutomirski: >>> >>>> The initial implementation is straightforward: highpid is simply a >>>> 64-bit counter. If a high-end system can fork every 3 ns (which >>>> would be amazing, given that just allocating a pid requires at >>>> atomic operation), it would take well over 1000 years for highpid to >>>> wrap. >>> >>> I'm not sure if I'm reading the patch correctly, but is the counter >>> namespaced? If yes, why? >> >> It's namespaced so that CRIU can migrate/restore a whole pid namespace. > > Oh well, this requirement is at odds with system-wide uniqueness. Is > CRIU really that important? :-)
Well, in this context it is. Since the main (if not the only) use-case for highpid is to read one, remember, then compare to new value, restoring it to wrong/arbitrary value will break the using applications in 100% cases.
Thus we really need the ability to restore this value.
Thanks, Pavel
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