block, bfq: Reorder struct bfq_iocq_bfqq_data

The size of struct bfq_iocq_bfqq_data can be reduced by moving a few
fields around.

On a x86_64, with allmodconfig, this shrinks the size from 144 to 128
bytes. The main benefit is to reduce the size of struct bfq_io_cq from
1360 to 1232.

This structure is stored in a dedicated slab cache. So reducing its size
improves cache usage.

Signed-off-by: Christophe JAILLET <[email protected]>
Reviewed-by: Yu Kuai <[email protected]>
Link: https://lore.kernel.org/r/79394db1befaa658e8066b8e3348073ce27d9d26.1754119538.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Jens Axboe <[email protected]>

Author: tititiou36

block/bfq-iosched.h

@@ -427,9 +427,6 @@ struct bfq_iocq_bfqq_data {
 	 */
 	bool saved_IO_bound;
 
-	u64 saved_io_start_time;
-	u64 saved_tot_idle_time;
-
 	/*
 	 * Same purpose as the previous fields for the values of the
 	 * field keeping the queue's belonging to a large burst
@@ -450,20 +447,23 @@ struct bfq_iocq_bfqq_data {
 	 */
 	unsigned int saved_weight;
 
+	u64 saved_io_start_time;
+	u64 saved_tot_idle_time;
+
 	/*
 	 * Similar to previous fields: save wr information.
 	 */
 	unsigned long saved_wr_coeff;
 	unsigned long saved_last_wr_start_finish;
 	unsigned long saved_service_from_wr;
 	unsigned long saved_wr_start_at_switch_to_srt;
-	unsigned int saved_wr_cur_max_time;
 	struct bfq_ttime saved_ttime;
+	unsigned int saved_wr_cur_max_time;
 
 	/* Save also injection state */
-	u64 saved_last_serv_time_ns;
 	unsigned int saved_inject_limit;
 	unsigned long saved_decrease_time_jif;
+	u64 saved_last_serv_time_ns;
 
 	/* candidate queue for a stable merge (due to close creation time) */
 	struct bfq_queue *stable_merge_bfqq;