Messages in this thread | | | Date | Wed, 16 Nov 2022 10:44:15 +0100 | From | Michal Hocko <> | Subject | Re: [External] Re: [PATCH v2] mm: add new syscall pidfd_set_mempolicy(). |
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On Wed 16-11-22 17:38:09, Zhongkun He wrote: > Hi Ying, thanks for your replay and suggestions. > > > > > I suggest to move the flags in "mode" parameter (MPOL_F_STATIC_NODES, > > MPOL_F_RELATIVE_NODES, MPOL_F_NUMA_BALANCING, etc.) to "flags" > > parameter, otherwise, why add it? > > The "flags" is used for future extension if any, just like > process_madvise() and set_mempolicy_home_node(). > Maybe it should be removed.
No, please! Even if there is no use for the flags now we are usually terrible at predicting future and potential extensions. MPOL_F* is kinda flags but for historical reasons it is a separate mode and we shouldn't create a new confusion when this is treated differently for pidfd based APIs.
> > And, how about add a "home_node" parameter? I don't think that it's a > > good idea to add another new syscall for pidfd_set_mempolicy_home_node() > > in the future.
Why would this be a bad idea?
> Good idea, but "home_node" is used for vma policy, not task policy. > It is possible to use it in pidfd_mbind() in the future.
I woould go with pidfd_set_mempolicy_home_node to counterpart an existing syscall.
-- Michal Hocko SUSE Labs
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