From ffc4e7595734cf768fa60cea8a4d545dfef8231a Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 19 Feb 2008 10:02:29 +0100 Subject: cfq-iosched: add hlist for browsing parallel to the radix tree It's cumbersome to browse a radix tree from start to finish, especially since we modify keys when a process exits. So add a hlist for the single purpose of browsing over all known cfq_io_contexts, used for exit, io prio change, etc. This fixes http://bugzilla.kernel.org/show_bug.cgi?id=9948 Signed-off-by: Jens Axboe --- block/blk-ioc.c | 35 +++++++++++++++-------------------- block/cfq-iosched.c | 38 ++++++++++++-------------------------- 2 files changed, 27 insertions(+), 46 deletions(-) (limited to 'block') diff --git a/block/blk-ioc.c b/block/blk-ioc.c index 4ae0929c6e38..e34df7c9fc36 100644 --- a/block/blk-ioc.c +++ b/block/blk-ioc.c @@ -17,17 +17,13 @@ static struct kmem_cache *iocontext_cachep; static void cfq_dtor(struct io_context *ioc) { - struct cfq_io_context *cic[1]; - int r; + if (!hlist_empty(&ioc->cic_list)) { + struct cfq_io_context *cic; - /* - * We don't have a specific key to lookup with, so use the gang - * lookup to just retrieve the first item stored. The cfq exit - * function will iterate the full tree, so any member will do. - */ - r = radix_tree_gang_lookup(&ioc->radix_root, (void **) cic, 0, 1); - if (r > 0) - cic[0]->dtor(ioc); + cic = list_entry(ioc->cic_list.first, struct cfq_io_context, + cic_list); + cic->dtor(ioc); + } } /* @@ -57,18 +53,16 @@ EXPORT_SYMBOL(put_io_context); static void cfq_exit(struct io_context *ioc) { - struct cfq_io_context *cic[1]; - int r; - rcu_read_lock(); - /* - * See comment for cfq_dtor() - */ - r = radix_tree_gang_lookup(&ioc->radix_root, (void **) cic, 0, 1); - rcu_read_unlock(); - if (r > 0) - cic[0]->exit(ioc); + if (!hlist_empty(&ioc->cic_list)) { + struct cfq_io_context *cic; + + cic = list_entry(ioc->cic_list.first, struct cfq_io_context, + cic_list); + cic->exit(ioc); + } + rcu_read_unlock(); } /* Called by the exitting task */ @@ -105,6 +99,7 @@ struct io_context *alloc_io_context(gfp_t gfp_flags, int node) ret->nr_batch_requests = 0; /* because this is 0 */ ret->aic = NULL; INIT_RADIX_TREE(&ret->radix_root, GFP_ATOMIC | __GFP_HIGH); + INIT_HLIST_HEAD(&ret->cic_list); ret->ioc_data = NULL; } diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index ca198e61fa65..0f962ecae91f 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1145,38 +1145,19 @@ static void cfq_put_queue(struct cfq_queue *cfqq) /* * Call func for each cic attached to this ioc. Returns number of cic's seen. */ -#define CIC_GANG_NR 16 static unsigned int call_for_each_cic(struct io_context *ioc, void (*func)(struct io_context *, struct cfq_io_context *)) { - struct cfq_io_context *cics[CIC_GANG_NR]; - unsigned long index = 0; - unsigned int called = 0; - int nr; + struct cfq_io_context *cic; + struct hlist_node *n; + int called = 0; rcu_read_lock(); - - do { - int i; - - /* - * Perhaps there's a better way - this just gang lookups from - * 0 to the end, restarting after each CIC_GANG_NR from the - * last key + 1. - */ - nr = radix_tree_gang_lookup(&ioc->radix_root, (void **) cics, - index, CIC_GANG_NR); - if (!nr) - break; - - called += nr; - index = 1 + (unsigned long) cics[nr - 1]->key; - - for (i = 0; i < nr; i++) - func(ioc, cics[i]); - } while (nr == CIC_GANG_NR); - + hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list) { + func(ioc, cic); + called++; + } rcu_read_unlock(); return called; @@ -1190,6 +1171,7 @@ static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic) spin_lock_irqsave(&ioc->lock, flags); radix_tree_delete(&ioc->radix_root, cic->dead_key); + hlist_del_rcu(&cic->cic_list); spin_unlock_irqrestore(&ioc->lock, flags); kmem_cache_free(cfq_ioc_pool, cic); @@ -1280,6 +1262,7 @@ cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) if (cic) { cic->last_end_request = jiffies; INIT_LIST_HEAD(&cic->queue_list); + INIT_HLIST_NODE(&cic->cic_list); cic->dtor = cfq_free_io_context; cic->exit = cfq_exit_io_context; elv_ioc_count_inc(ioc_count); @@ -1501,6 +1484,7 @@ cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc, rcu_assign_pointer(ioc->ioc_data, NULL); radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd); + hlist_del_rcu(&cic->cic_list); spin_unlock_irqrestore(&ioc->lock, flags); cfq_cic_free(cic); @@ -1561,6 +1545,8 @@ static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, spin_lock_irqsave(&ioc->lock, flags); ret = radix_tree_insert(&ioc->radix_root, (unsigned long) cfqd, cic); + if (!ret) + hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list); spin_unlock_irqrestore(&ioc->lock, flags); radix_tree_preload_end(); -- cgit v1.2.3-70-g09d2