On Thu, May 29, 2014 at 11:05:40AM +0200, Paolo Valente wrote: > This patch introduces an heuristic that reduces latency when the > I/O-request pool is saturated. This goal is achieved by disabling > device idling, for non-weight-raised queues, when there are weight- > raised queues with pending or in-flight requests. In fact, as > explained in more detail in the comment to the function > bfq_bfqq_must_not_expire(), this reduces the rate at which processes > associated with non-weight-raised queues grab requests from the pool, > thereby increasing the probability that processes associated with > weight-raised queues get a request immediately (or at least soon) when > they need one.
Wouldn't it be more straight-forward to simply control how many requests each queue consume by returning ELV_MQUEUE_NO? Seeky ones do benefit from larger number of requests in elevator but to only certain number given the fifo timeout anyway and controlling that explicitly would be a lot easier to anticipate the behavior of than playing roulette with random request allocation failures. 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/
