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 <christophe.jaillet@wanadoo.fr>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/79394db1befaa658e8066b8e3348073ce27d9d26.1754119538.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index 687a3a7ba7847868a63a2b41dfcbf6344b0259d3..0b4704932d72b428d6bba16c378438f94cb383d2 100644 (file)
--- a/block/bfq-iosched.h
+++ b/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
@@ -450,6 +447,9 @@ 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.
         */
@@ -457,13 +457,13 @@ struct bfq_iocq_bfqq_data {
        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;