On Thu 14-10-21 15:00:22, Aneesh Kumar K.V wrote:
> Michal Hocko <mhocko@xxxxxxxx> writes:
>
> > On Wed 13-10-21 18:53:55, Aneesh Kumar K.V wrote:
> >> On 10/13/21 18:46, Andi Kleen wrote:
> >> >
> >> > > The difference with MPOL_BIND is the ability to specify a preferred node
> >> > > which is the first node in the nodemask argument passed.
> >> >
> >> > That's always the one with the lowest number. Isn't that quite limiting
> >> > in practice?
> >> >
> >> > It seems if you really want to do that you would need another argument.
> >> >
> >> Yes. But that would make it a new syscall. Should we do that?
> >
> > Yes, I do not see any reasonable to cram this into the existing syscall.
> > I am not yet sure what the syscall should look like though. I can see
> > two usecases, one of the is a very specific node allocation fallback
> > order requirement and another one is preferrence for a cpu less node
> > over other nodes. Both are slightly different.
>
> How about
>
> SYSCALL_DEFINE5(preferred_mbind, unsigned long, start, unsigned long, len,
> unsigned long, preferred_node, const unsigned long __user *, nmask,
> unsigned long, maxnode)
> {
> return kernel_mbind(start, len, MPOL_PREFERRED_STRICT, preferred_node,
> nmask, maxnode, 0);
> }
Semantic? How does it interact with MPOL_PREFERRED_MANY, MPOL_BIND and
other others?
Besides that it would be really great to finish the discussion about the
usecase before suggesting a new userspace API.
--
Michal Hocko
SUSE Labs
