On 26.5.2016 21:21, Tejun Heo wrote:
> Hello,
>
> On Thu, May 26, 2016 at 11:19:06AM +0200, Vlastimil Babka wrote:
>>> if (is_atomic) {
>>> margin = 3;
>>>
>>> if (chunk->map_alloc <
>>> - chunk->map_used + PCPU_ATOMIC_MAP_MARGIN_LOW &&
>>> - pcpu_async_enabled)
>>> - schedule_work(&chunk->map_extend_work);
>>> + chunk->map_used + PCPU_ATOMIC_MAP_MARGIN_LOW) {
>>> + if (list_empty(&chunk->map_extend_list)) {
>
>> So why this list_empty condition? Doesn't it deserve a comment then? And
>
> Because doing list_add() twice corrupts the list. I'm not sure that
> deserves a comment. We can do list_move() instead but that isn't
> necessarily better.
Ugh, right, somehow I thought it was testing &pcpu_map_extend_chunks.
My second question was based on the assumption that the list can have only one
item. Sorry about the noise.
>> isn't using a list an overkill in that case?
>
> That would require rebalance work to scan all chunks whenever it's
> scheduled and if a lot of atomic allocations are taking place, it has
> some possibility to become expensive with a lot of chunks.
>
> Thanks.
>
