Messages in this thread | ![/](/images/icornerl.gif) | | Date | Wed, 15 Feb 2023 12:12:52 -0500 | Subject | Re: [PATCH 1/1] rseq.2: New man page for the rseq(2) API | From | Mathieu Desnoyers <> |
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On 2023-02-15 12:09, Mathieu Desnoyers wrote: > On 2023-02-14 20:20, G. Branden Robinson wrote: [...] >> >>>> +user-space performs any side-effect >>>> +(e.g. storing to memory). >>>> +.IP >>>> +This field is always guaranteed to hold a valid CPU number in the >>>> range >>>> +[ 0 .. nr_possible_cpus - 1 ]. >>> >>> Please use interval notation: >>> [0, nr_possible_cpus) >>> or >>> [0, nr_possible_cpus - 1] >>> whichever looks better to you. >>> >>> We did some consistency fix recently: >>> <https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/commit/?id=147a60d792a5db8f3cb93ea16eefb73e16c1fb91> >>> >>> Also, do we have a more standard way of saying nr_possible_cpus? >>> Should we say nproc? > > nproc(1) means: > > Print the number of processing units available to the current > process, which may be less than the number of online processors > > Which is the number of cpus currently available (AFAIU the result of the > cpuset and sched affinity). > > What I really mean here is the maximum value for possible cpus which can > be hotplugged into the system. So it's not the maximum number of > possible CPUs per se, but rather the maximum enabled bit in the possible > CPUs mask. > > Note that we could express this differently as well: rather than saying > that it guarantees a value in the range [0, nr_possible_cpus - 1], we > could say that the values are guaranteed to be part of the possible cpus > mask, which would actually more accurate in case the possible cpus mask > has a hole (it tends to happen with things like lxc containers nowadays). > > Do you agree that we should favor expressing this in terms of belonging > to the possible cpumask set rather than a range starting from 0 ?
Actually, the field may contain the value 0 even if 0 is not part of the possible cpumask. So forget what I just said about being guaranteed to be part of the possible cpus mask.
Thoughts ?
Thanks,
Mathieu
> > Thanks, > > Mathieu >
-- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com
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