* Ingo Molnar <mi...@kernel.org> wrote:
>
> * Linus Torvalds <torva...@linux-foundation.org> wrote:
>
> > On Tue, Mar 29, 2016 at 4:44 AM, Ingo Molnar <mi...@kernel.org> wrote:
> > >
> > > Harmonizing thread_info::flags does not look easy, given how much
> > > assembly code
> > > accesses this field.
> >
> > It might not be too bad.
> >
> > For 32-bit architectures (which is still most of them), it's just a
> >
> > unsigned int/long -> atomic_t
> >
> > and for 64-bit architectures you end up with three choices:
> >
> > - it's already 32-bit (alpha, ia64, x86):
> >
> > unsigned int -> atomic_t
> >
> > - little-endian long:
> >
> > atomic_t flags
> > unsigned int padding;
> >
> > - big-endian long (only powerpc? Maybe there's a big-endian MIPS still?)
> >
> > unsigned int padding;
> > atomic_t flags;
>
> Hm, that indeed sounds fairly nice and doable - I thought some architectures
> do
> have a task flag above bit 31, but that does not appear to be so ...
>
> Right now we seem to have 27 bits defined in include/linux/sched.h, with 5
> more
> bits left for the future. Here's their current usage histogram in the kernel
> source:
>
> PF_KTHREAD : 68
> PF_MEMALLOC : 65
Argh, my reading comprehension skills suck today.
That's a totally useless analysis of task_struct::flags, while we want to
convert
thread_info::flags...
Thanks,
Ingo
