cfq-iosched: fold cfq_find_alloc_queue() into cfq_get_queue()
cfq_find_alloc_queue() checks whether a queue actually needs to be allocated, which is unnecessary as its sole caller, cfq_get_queue(), only calls it if so. Also, the oom queue fallback logic is scattered between cfq_get_queue() and cfq_find_alloc_queue(). There really isn't much going on in the latter and things can be made simpler by folding it into cfq_get_queue(). This patch collapses cfq_find_alloc_queue() into cfq_get_queue(). The change is fairly straight-forward with one exception - async_cfqq is now initialized to NULL and the "!is_sync" test in the last if conditional is replaced with "async_cfqq" test. This is because gcc (5.1.1) gets confused for some reason and warns that async_cfqq may be used uninitialized otherwise. Oh well, the code isn't necessarily worse this way. This patch doesn't cause any functional difference. v2: Updated to reflect GFP_ATOMIC -> GPF_NOWAIT. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Arianna Avanzini <avanzini.arianna@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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1 changed files with 15 additions and 34 deletions
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@ -3640,33 +3640,6 @@ static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
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static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { }
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static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { }
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#endif /* CONFIG_CFQ_GROUP_IOSCHED */
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#endif /* CONFIG_CFQ_GROUP_IOSCHED */
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static struct cfq_queue *
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cfq_find_alloc_queue(struct cfq_data *cfqd, struct cfq_group *cfqg, bool is_sync,
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struct cfq_io_cq *cic, struct bio *bio)
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{
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struct cfq_queue *cfqq;
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cfqq = cic_to_cfqq(cic, is_sync);
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/*
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* Always try a new alloc if we fell back to the OOM cfqq
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* originally, since it should just be a temporary situation.
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*/
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if (!cfqq || cfqq == &cfqd->oom_cfqq) {
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cfqq = kmem_cache_alloc_node(cfq_pool,
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GFP_NOWAIT | __GFP_ZERO,
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cfqd->queue->node);
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if (cfqq) {
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cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
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cfq_init_prio_data(cfqq, cic);
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cfq_link_cfqq_cfqg(cfqq, cfqg);
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cfq_log_cfqq(cfqd, cfqq, "alloced");
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} else
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cfqq = &cfqd->oom_cfqq;
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}
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return cfqq;
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}
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static struct cfq_queue **
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static struct cfq_queue **
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cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
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cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
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{
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{
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@ -3691,7 +3664,7 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
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{
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{
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int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
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int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
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int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
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int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
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struct cfq_queue **async_cfqq;
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struct cfq_queue **async_cfqq = NULL;
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struct cfq_queue *cfqq;
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struct cfq_queue *cfqq;
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struct cfq_group *cfqg;
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struct cfq_group *cfqg;
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@ -3714,12 +3687,20 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
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goto out;
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goto out;
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}
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}
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cfqq = cfq_find_alloc_queue(cfqd, cfqg, is_sync, cic, bio);
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cfqq = kmem_cache_alloc_node(cfq_pool, GFP_NOWAIT | __GFP_ZERO,
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cfqd->queue->node);
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if (!cfqq) {
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cfqq = &cfqd->oom_cfqq;
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goto out;
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}
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/*
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cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
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* pin the queue now that it's allocated, scheduler exit will prune it
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cfq_init_prio_data(cfqq, cic);
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*/
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cfq_link_cfqq_cfqg(cfqq, cfqg);
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if (!is_sync && cfqq != &cfqd->oom_cfqq) {
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cfq_log_cfqq(cfqd, cfqq, "alloced");
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if (async_cfqq) {
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/* a new async queue is created, pin and remember */
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cfqq->ref++;
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cfqq->ref++;
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*async_cfqq = cfqq;
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*async_cfqq = cfqq;
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}
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}
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@ -4469,7 +4450,7 @@ static int cfq_init_queue(struct request_queue *q, struct elevator_type *e)
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cfqd->prio_trees[i] = RB_ROOT;
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cfqd->prio_trees[i] = RB_ROOT;
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/*
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/*
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* Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
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* Our fallback cfqq if cfq_get_queue() runs into OOM issues.
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* Grab a permanent reference to it, so that the normal code flow
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* Grab a permanent reference to it, so that the normal code flow
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* will not attempt to free it. oom_cfqq is linked to root_group
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* will not attempt to free it. oom_cfqq is linked to root_group
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* but shouldn't hold a reference as it'll never be unlinked. Lose
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* but shouldn't hold a reference as it'll never be unlinked. Lose
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