Messages in this thread | | | From | Lai Jiangshan <> | Date | Fri, 28 Aug 2020 12:03:54 +0800 | Subject | Re: [RFC][PATCH 6/7] freelist: Lock less freelist |
| |
On Fri, Aug 28, 2020 at 12:23 AM Peter Zijlstra <peterz@infradead.org> wrote:
> +static inline void __freelist_add(struct freelist_node *node, struct freelist_head *list) > +{ > + /* > + * Since the refcount is zero, and nobody can increase it once it's > + * zero (except us, and we run only one copy of this method per node at > + * a time, i.e. the single thread case), then we know we can safely
> + > + /* > + * OK, the head must have changed on us, but we still need to decrement > + * the refcount we increased. > + */ > + refs = atomic_fetch_add(-1, &prev->refs); > + if (refs == REFS_ON_FREELIST + 1) > + __freelist_add(prev, list);
I'm curious whether it is correct to just set the prev->refs to zero and return @prev? So that it can remove an unneeded "add()&get()" pair (although in an unlikely branch) and __freelist_add() can be folded into freelist_add() for tidier code.
Thanks Lai.
| |