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| author | Jens Axboe <axboe@suse.de> | 2006-07-19 05:07:12 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@nelson.home.kernel.dk> | 2006-09-30 20:29:37 +0200 |
| commit | 4050cf1674c632c73801a561689543d4887df2ef (patch) | |
| tree | f7a3e55857e917bb129d16d27458c2ff897a1864 /block/cfq-iosched.c | |
| parent | e4313dd423148fa729571b50c06cbc0bedf5c494 (diff) | |
| download | lwn-4050cf1674c632c73801a561689543d4887df2ef.tar.gz lwn-4050cf1674c632c73801a561689543d4887df2ef.zip | |
[PATCH] cfq-iosched: use new io context counting mechanism
It's ok if the read path is a lot more costly, as long as inc/dec is
really cheap. The inc/dec will happen for each created/freed io context,
while the reading only happens when a disk queue exits.
Signed-off-by: Jens Axboe <axboe@suse.de>
Diffstat (limited to 'block/cfq-iosched.c')
| -rw-r--r-- | block/cfq-iosched.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 33e0b0c5e31d..c988aa75dd55 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -46,7 +46,7 @@ static int cfq_slice_idle = HZ / 125; static kmem_cache_t *cfq_pool; static kmem_cache_t *cfq_ioc_pool; -static atomic_t ioc_count = ATOMIC_INIT(0); +static DEFINE_PER_CPU(unsigned long, ioc_count); static struct completion *ioc_gone; #define CFQ_PRIO_LISTS IOPRIO_BE_NR @@ -1078,7 +1078,9 @@ static void cfq_free_io_context(struct io_context *ioc) freed++; } - if (atomic_sub_and_test(freed, &ioc_count) && ioc_gone) + elv_ioc_count_mod(ioc_count, -freed); + + if (ioc_gone && !elv_ioc_count_read(ioc_count)) complete(ioc_gone); } @@ -1154,7 +1156,7 @@ cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) INIT_LIST_HEAD(&cic->queue_list); cic->dtor = cfq_free_io_context; cic->exit = cfq_exit_io_context; - atomic_inc(&ioc_count); + elv_ioc_count_inc(ioc_count); } return cic; @@ -1319,7 +1321,7 @@ cfq_drop_dead_cic(struct io_context *ioc, struct cfq_io_context *cic) WARN_ON(!list_empty(&cic->queue_list)); rb_erase(&cic->rb_node, &ioc->cic_root); kmem_cache_free(cfq_ioc_pool, cic); - atomic_dec(&ioc_count); + elv_ioc_count_dec(ioc_count); } static struct cfq_io_context * @@ -2165,7 +2167,7 @@ static void __exit cfq_exit(void) ioc_gone = &all_gone; /* ioc_gone's update must be visible before reading ioc_count */ smp_wmb(); - if (atomic_read(&ioc_count)) + if (elv_ioc_count_read(ioc_count)) wait_for_completion(ioc_gone); synchronize_rcu(); cfq_slab_kill(); |