Re: [PATCH] Fix argument checking in sched_setaffinity

[Andi Kleen <ak@suse.de>]

On Tue, Sep 07, 2004 at 07:40:53AM -0700, Linus Torvalds wrote:
> >     No doubt Andi will veto this for mbind/mempolicy, because it breaks
> >     libnuma's he has in the field - a reasonable concern. 
> 
> Now, it will _only_ break systems that are _both_ 64-bit _and_ big-endian. 
> Little-endian or 32-bit boxes will never care.
> 
> There aren't that many of those machines. I've got one right here (ppc64), 
> but that particular one is guaranteed not to break if only because it's 
> running a 32-bit user space.

ppc64 libnuma is not deployed - the current numactl releases
still don't have the system call numbers and nobody told me 
about hacking them in.

So for me breaking ppc64 would be no problem.

> 
> So it's ppc64, sparc64, s390x and sh64. I suspect the breakage is 
> basically zero, since not only aren't there _that_ many machines out 
> there, the percentage of them that use setaffinity or mbind is likely not 
> that high either.

For mbind() breaking existing ppc64 users is unlikely I agree.

For setaffinity I am not so sure. The system call is around
for a long time and has been used in standard utilities
in distributions also for quite some time.

Also it is commonly used in real time applications. 

So in short I think changing mbind to u32 would be fine,
but I wouldn't do it for sched_setaffinity() 

-Andi