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percpu_ida: make percpu_ida percpu size/batch configurable 

Make percpu_ida percpu size/batch configurable. The block-mq-tag will
use it.

After block-mq uses percpu_ida to manage tags, performance is improved.
My test is done in a 2 sockets machine, 12 process cross the 2 sockets.
So if there is lock contention or ipi, should be stressed heavily.
Testing is done for null-blk.

hw_queue_depth	nopatch iops	patch iops
64		~800k/s		~1470k/s
2048		~4470k/s	~4340k/s

Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Shaohua Li 2013-10-15 09:05:01 +08:00 committed by Jens Axboe
parent 098faf5805
commit e26b53d0b2
2 changed files with 28 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
include/linux/percpu_ida.h
View File

@ -16,6 +16,8 @@ struct percpu_ida {
* percpu_ida_init()
*/
unsigned nr_tags;
unsigned percpu_max_size;
unsigned percpu_batch_size;
struct percpu_ida_cpu __percpu *tag_cpu;
@ -51,10 +53,24 @@ struct percpu_ida {
} ____cacheline_aligned_in_smp;
};
/*
* Number of tags we move between the percpu freelist and the global freelist at
* a time
*/
#define IDA_DEFAULT_PCPU_BATCH_MOVE 32U
/* Max size of percpu freelist, */
#define IDA_DEFAULT_PCPU_SIZE ((IDA_DEFAULT_PCPU_BATCH_MOVE * 3) / 2)
int percpu_ida_alloc(struct percpu_ida *pool, gfp_t gfp);
void percpu_ida_free(struct percpu_ida *pool, unsigned tag);
void percpu_ida_destroy(struct percpu_ida *pool);
int percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags);
int __percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags,
unsigned long max_size, unsigned long batch_size);
static inline int percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags)
{
return __percpu_ida_init(pool, nr_tags, IDA_DEFAULT_PCPU_SIZE,
IDA_DEFAULT_PCPU_BATCH_MOVE);
}
#endif /* __PERCPU_IDA_H__ */

28
lib/percpu_ida.c
View File

@ -30,15 +30,6 @@
#include <linux/spinlock.h>
#include <linux/percpu_ida.h>
/*
* Number of tags we move between the percpu freelist and the global freelist at
* a time
*/
#define IDA_PCPU_BATCH_MOVE 32U
/* Max size of percpu freelist, */
#define IDA_PCPU_SIZE ((IDA_PCPU_BATCH_MOVE * 3) / 2)
struct percpu_ida_cpu {
/*
* Even though this is percpu, we need a lock for tag stealing by remote
@ -78,7 +69,7 @@ static inline void steal_tags(struct percpu_ida *pool,
struct percpu_ida_cpu *remote;
for (cpus_have_tags = cpumask_weight(&pool->cpus_have_tags);
cpus_have_tags * IDA_PCPU_SIZE > pool->nr_tags / 2;
cpus_have_tags * pool->percpu_max_size > pool->nr_tags / 2;
cpus_have_tags--) {
cpu = cpumask_next(cpu, &pool->cpus_have_tags);
@ -123,7 +114,7 @@ static inline void alloc_global_tags(struct percpu_ida *pool,
{
move_tags(tags->freelist, &tags->nr_free,
pool->freelist, &pool->nr_free,
min(pool->nr_free, IDA_PCPU_BATCH_MOVE));
min(pool->nr_free, pool->percpu_batch_size));
}
static inline unsigned alloc_local_tag(struct percpu_ida *pool,
@ -245,17 +236,17 @@ void percpu_ida_free(struct percpu_ida *pool, unsigned tag)
wake_up(&pool->wait);
}
if (nr_free == IDA_PCPU_SIZE) {
if (nr_free == pool->percpu_max_size) {
spin_lock(&pool->lock);
/*
* Global lock held and irqs disabled, don't need percpu
* lock
*/
if (tags->nr_free == IDA_PCPU_SIZE) {
if (tags->nr_free == pool->percpu_max_size) {
move_tags(pool->freelist, &pool->nr_free,
tags->freelist, &tags->nr_free,
IDA_PCPU_BATCH_MOVE);
pool->percpu_batch_size);
wake_up(&pool->wait);
}
@ -292,7 +283,8 @@ EXPORT_SYMBOL_GPL(percpu_ida_destroy);
* Allocation is percpu, but sharding is limited by nr_tags - for best
* performance, the workload should not span more cpus than nr_tags / 128.
*/
int percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags)
int __percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags,
unsigned long max_size, unsigned long batch_size)
{
unsigned i, cpu, order;
@ -301,6 +293,8 @@ int percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags)
init_waitqueue_head(&pool->wait);
spin_lock_init(&pool->lock);
pool->nr_tags = nr_tags;
pool->percpu_max_size = max_size;
pool->percpu_batch_size = batch_size;
/* Guard against overflow */
if (nr_tags > (unsigned) INT_MAX + 1) {
@ -319,7 +313,7 @@ int percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags)
pool->nr_free = nr_tags;
pool->tag_cpu = __alloc_percpu(sizeof(struct percpu_ida_cpu) +
IDA_PCPU_SIZE * sizeof(unsigned),
pool->percpu_max_size * sizeof(unsigned),
sizeof(unsigned));
if (!pool->tag_cpu)
goto err;
@ -332,4 +326,4 @@ err:
percpu_ida_destroy(pool);
return -ENOMEM;
}
EXPORT_SYMBOL_GPL(percpu_ida_init);
EXPORT_SYMBOL_GPL(__percpu_ida_init);