Re: [RFC tip/locking/lockdep v5 15/17] lockdep: Reduce the size of lock_list

Boqun Feng
2018-02-23T12:37:00Z

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On Fri, Feb 23, 2018 at 12:38:43PM +0100, Peter Zijlstra wrote:
> On Thu, Feb 22, 2018 at 03:09:02PM +0800, Boqun Feng wrote:
> > diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
> > index a1f91f8680bd..3fce8dbf5091 100644
> > --- a/include/linux/lockdep.h
> > +++ b/include/linux/lockdep.h
> > @@ -186,11 +186,11 @@ struct lock_list {
> > struct list_head entry;
> > struct lock_class *class;
> > struct stack_trace trace;
> > - int distance;
> > + u16 distance;
> > /* bitmap of different dependencies from head to this */
> > - u16 dep;
> > + u8 dep;
> > /* used by BFS to record whether this is picked as a recursive read */
> > - u16 is_rr;
> > + bool is_rr;
>
> Don't use bool, use u8 if you want a single byte. sizeof(_Bool) is part
> of the architecture ABI and can be up to 4 bytes (well really anything,
> but I've not seen it bigger than 4 bytes for any sane implementation).

Got it, thanks!

Regards,
Boqun

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