On Tue, Mar 29, 2016 at 03:05:14PM +0200, Ingo Molnar wrote: > > * 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...
Actually we want to convert that one too :-) In fact I planned to start there.
