block,bfq: refactor device-idling logic
The logic that decides whether to idle the device is scattered across
three functions. Almost all of the logic is in the function
bfq_bfqq_may_idle, but (1) part of the decision is made in
bfq_update_idle_window, and (2) the function bfq_bfqq_must_idle may
switch off idling regardless of the output of bfq_bfqq_may_idle. In
addition, both bfq_update_idle_window and bfq_bfqq_must_idle make
their decisions as a function of parameters that are used, for similar
purposes, also in bfq_bfqq_may_idle. This commit addresses these
issues by moving all the logic into bfq_bfqq_may_idle.
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index 1f74d71..fb28c25 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -348,11 +348,11 @@ struct bfq_io_cq {
uint64_t blkcg_serial_nr; /* the current blkcg serial */
#endif
/*
- * Snapshot of the idle window before merging; taken to
- * remember this value while the queue is merged, so as to be
- * able to restore it in case of split.
+ * Snapshot of the has_short_time flag before merging; taken
+ * to remember its value while the queue is merged, so as to
+ * be able to restore it in case of split.
*/
- bool saved_idle_window;
+ bool saved_has_short_ttime;
/*
* Same purpose as the previous two fields for the I/O bound
* classification of a queue.
@@ -626,7 +626,7 @@ enum bfqq_state_flags {
* without idling the device
*/
BFQQF_fifo_expire, /* FIFO checked in this slice */
- BFQQF_idle_window, /* slice idling enabled */
+ BFQQF_has_short_ttime, /* queue has a short think time */
BFQQF_sync, /* synchronous queue */
BFQQF_IO_bound, /*
* bfqq has timed-out at least once
@@ -655,7 +655,7 @@ BFQ_BFQQ_FNS(busy);
BFQ_BFQQ_FNS(wait_request);
BFQ_BFQQ_FNS(non_blocking_wait_rq);
BFQ_BFQQ_FNS(fifo_expire);
-BFQ_BFQQ_FNS(idle_window);
+BFQ_BFQQ_FNS(has_short_ttime);
BFQ_BFQQ_FNS(sync);
BFQ_BFQQ_FNS(IO_bound);
BFQ_BFQQ_FNS(in_large_burst);