On 1/17/24 01:23, zhaoyang.huang wrote:
+static enum dd_prio dd_req_ioprio(struct request *rq)
+{
+ enum dd_prio prio;
+ const u8 ioprio_class = dd_rq_ioclass(rq);
+#ifdef CONFIG_ACTIVITY_BASED_IOPRIO
+ struct bio *bio;
+ struct bio_vec bv;
+ struct bvec_iter iter;
+ struct page *page;
+ int gen = 0;
+ int cnt = 0;
+
+ if (req_op(rq) == REQ_OP_READ) {
+ __rq_for_each_bio(bio, rq) {
+ bio_for_each_bvec(bv, bio, iter) {
+ page = bv.bv_page;
+ gen += PageWorkingset(page) ? 1 : 0;
+ cnt++;
+ }
+ }
+ prio = (gen >= cnt / 2) ? ioprio_class_to_prio[IOPRIO_CLASS_RT] :
+ ioprio_class_to_prio[ioprio_class];
+ } else
+ prio = ioprio_class_to_prio[ioprio_class];
+#else
+ prio = ioprio_class_to_prio[ioprio_class];
+#endif
+ return prio;
+}
I don't like it that code is introduced in the mq-deadline scheduler
that accesses page cache information. Isn't that a layering violation?
Additionally, this approach only works for buffered I/O and not for
direct I/O. Shouldn't the I/O submitter set the I/O priority instead of
deciding the I/O priority in the mq-deadline scheduler?
Bart.
