It's clearly been a while since someone looked at this, so I gave it a
quick shot. There are few issues in here:
- Random bundling of members that are mostly read-only and often written
- Random holes that need not be there
This moves the most frequently used bits into cacheline 1 and 2, with
the 2nd one being more write intensive than the first one, which is
basically read-only.
Outside of making this work a bit more efficiently, it also reduces the
size of struct request_queue for my test setup from 864 bytes (spanning
14 cachelines!) to 832 bytes and 13 cachelines.
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 17c0a7d0d319..185ed3770e3a 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -367,59 +367,51 @@ struct blk_independent_access_ranges {
};
struct request_queue {
- struct request *last_merge;
- struct elevator_queue *elevator;
-
- struct percpu_ref q_usage_counter;
+ /*
+ * The queue owner gets to use this for whatever they like.
+ * ll_rw_blk doesn't touch it.
+ */
+ void *queuedata;
- struct blk_queue_stats *stats;
- struct rq_qos *rq_qos;
- struct mutex rq_qos_mutex;
+ struct elevator_queue *elevator;
const struct blk_mq_ops *mq_ops;
/* sw queues */
struct blk_mq_ctx __percpu *queue_ctx;
+ /*
+ * various queue flags, see QUEUE_* below
+ */
+ unsigned long queue_flags;
+
+ unsigned int rq_timeout;
+
unsigned int queue_depth;
+ refcount_t refs;
+
/* hw dispatch queues */
- struct xarray hctx_table;
unsigned int nr_hw_queues;
+ struct xarray hctx_table;
- /*
- * The queue owner gets to use this for whatever they like.
- * ll_rw_blk doesn't touch it.
- */
- void *queuedata;
-
- /*
- * various queue flags, see QUEUE_* below
- */
- unsigned long queue_flags;
- /*
- * Number of contexts that have called blk_set_pm_only(). If this
- * counter is above zero then only RQF_PM requests are processed.
- */
- atomic_t pm_only;
+ struct percpu_ref q_usage_counter;
- /*
- * ida allocated id for this queue. Used to index queues from
- * ioctx.
- */
- int id;
+ struct request *last_merge;
spinlock_t queue_lock;
- struct gendisk *disk;
+ int quiesce_depth;
- refcount_t refs;
+ struct gendisk *disk;
/*
* mq queue kobject
*/
struct kobject *mq_kobj;
+ struct queue_limits limits;
+
#ifdef CONFIG_BLK_DEV_INTEGRITY
struct blk_integrity integrity;
#endif /* CONFIG_BLK_DEV_INTEGRITY */
@@ -430,24 +422,40 @@ struct request_queue {
#endif
/*
- * queue settings
+ * Number of contexts that have called blk_set_pm_only(). If this
+ * counter is above zero then only RQF_PM requests are processed.
*/
- unsigned long nr_requests; /* Max # of requests */
+ atomic_t pm_only;
+
+ struct blk_queue_stats *stats;
+ struct rq_qos *rq_qos;
+ struct mutex rq_qos_mutex;
+
+ /*
+ * ida allocated id for this queue. Used to index queues from
+ * ioctx.
+ */
+ int id;
unsigned int dma_pad_mask;
+ /*
+ * queue settings
+ */
+ unsigned long nr_requests; /* Max # of requests */
+
#ifdef CONFIG_BLK_INLINE_ENCRYPTION
struct blk_crypto_profile *crypto_profile;
struct kobject *crypto_kobject;
#endif
- unsigned int rq_timeout;
-
struct timer_list timeout;
struct work_struct timeout_work;
atomic_t nr_active_requests_shared_tags;
+ unsigned int required_elevator_features;
+
struct blk_mq_tags *sched_shared_tags;
struct list_head icq_list;
@@ -458,11 +466,12 @@ struct request_queue {
struct mutex blkcg_mutex;
#endif
- struct queue_limits limits;
+ int node;
- unsigned int required_elevator_features;
+ spinlock_t requeue_lock;
+ struct list_head requeue_list;
+ struct delayed_work requeue_work;
- int node;
#ifdef CONFIG_BLK_DEV_IO_TRACE
struct blk_trace __rcu *blk_trace;
#endif
@@ -472,10 +481,6 @@ struct request_queue {
struct blk_flush_queue *fq;
struct list_head flush_list;
- struct list_head requeue_list;
- spinlock_t requeue_lock;
- struct delayed_work requeue_work;
-
struct mutex sysfs_lock;
struct mutex sysfs_dir_lock;
@@ -500,8 +505,6 @@ struct request_queue {
*/
struct mutex mq_freeze_lock;
- int quiesce_depth;
-
struct blk_mq_tag_set *tag_set;
struct list_head tag_set_list;
--
Jens Axboe
