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[PATCH] [BLOCK] cfq-iosched: change cfq io context linking from list to tree

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On setups with many disks, we spend a considerable amount of time
looking up the process-disk mapping on each queue of io. Testing with
a NULL based block driver, this costs 40-50% reduction in throughput
for 1000 disks.

Signed-off-by: Jens Axboe <axboe@suse.de>
This commit is contained in:
Jens Axboe
2006-03-28 08:59:01 +02:00
parent 329b10bb0f
commit e2d74ac066
3 changed files with 114 additions and 124 deletions
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14
include/linux/blkdev.h
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@ -55,13 +55,11 @@ struct as_io_context {
struct cfq_queue;
struct cfq_io_context {
/*
* circular list of cfq_io_contexts belonging to a process io context
*/
struct list_head list;
struct cfq_queue *cfqq[2];
struct rb_node rb_node;
void *key;
struct cfq_queue *cfqq[2];
struct io_context *ioc;
unsigned long last_end_request;
@ -72,8 +70,8 @@ struct cfq_io_context {
struct list_head queue_list;
void (*dtor)(struct cfq_io_context *);
void (*exit)(struct cfq_io_context *);
void (*dtor)(struct io_context *); /* destructor */
void (*exit)(struct io_context *); /* called on task exit */
};
/*
@ -94,7 +92,7 @@ struct io_context {
int nr_batch_requests; /* Number of requests left in the batch */
struct as_io_context *aic;
struct cfq_io_context *cic;
struct rb_root cic_root;
};
void put_io_context(struct io_context *ioc);