Hello, On Sat, Apr 19, 2014 at 06:43:41PM +0800, Lai Jiangshan wrote: > On 04/19/2014 01:17 AM, Tejun Heo wrote: > It only frees one layer. And the ida_pre_get() for the next ida_get_new*() > will allocation it back again. The aim "Throw away extra resources one by one" > can't be achieved. It can't keep its memory footprint minimal.
Isn't the point not keeping the memory around per-ida between allocations which can be arbitrarily long? Why isn't it achieved? > > I think the right > > thing to do is implementing ida_preload() which is simliar to > > idr_preload() and do away with per-ida layer cache. > > Yes and no. > > We need a static private ida_preload() for ida_simple_get() only. > > Because the IDA doesn't have any query-function, so IDA's own synchronization > is enough for all use cases, IDA should off-loads the caller's > synchronization burden. Hmmm? And why can't that use preload on its own? > In my todo-list, IDA only needs the following functions. other functions > will be deprecated and scheduled to be removed: > void ida_destroy(struct ida *ida); > void ida_init(struct ida *ida); > int ida_simple_get(struct ida *ida, unsigned int start, unsigned int > end, > gfp_t gfp_mask); > void ida_simple_remove(struct ida *ida, unsigned int id); > > (I don't think we need any query-function, But...) > If in the future we need some query-functions such as: > ida_is_this_id_allocated() > ida_find_next_[un]allocated_id(), > In this case, we can expose the ida_preload() and ida_alloc() at the same > time that > we introduce the query-functions. Regardless of interface, we can still switch to per-cpu layer caching which would make this per-ida allocation issue go away. I'd much prefer to see that than debating the (dis)merits of this patch. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
