c7c22e4d5c
This patch adds support for controlling the IO completion CPU of either all requests on a queue, or on a per-request basis. We export a sysfs variable (rq_affinity) which, if set, migrates completions of requests to the CPU that originally submitted it. A bio helper (bio_set_completion_cpu()) is also added, so that queuers can ask for completion on that specific CPU. In testing, this has been show to cut the system time by as much as 20-40% on synthetic workloads where CPU affinity is desired. This requires a little help from the architecture, so it'll only work as designed for archs that are using the new generic smp helper infrastructure. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
74 lines
2.1 KiB
C
74 lines
2.1 KiB
C
#ifndef BLK_INTERNAL_H
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#define BLK_INTERNAL_H
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/* Amount of time in which a process may batch requests */
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#define BLK_BATCH_TIME (HZ/50UL)
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/* Number of requests a "batching" process may submit */
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#define BLK_BATCH_REQ 32
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extern struct kmem_cache *blk_requestq_cachep;
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extern struct kobj_type blk_queue_ktype;
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void init_request_from_bio(struct request *req, struct bio *bio);
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void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
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struct bio *bio);
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void __blk_queue_free_tags(struct request_queue *q);
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void blk_unplug_work(struct work_struct *work);
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void blk_unplug_timeout(unsigned long data);
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struct io_context *current_io_context(gfp_t gfp_flags, int node);
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int ll_back_merge_fn(struct request_queue *q, struct request *req,
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struct bio *bio);
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int ll_front_merge_fn(struct request_queue *q, struct request *req,
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struct bio *bio);
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int attempt_back_merge(struct request_queue *q, struct request *rq);
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int attempt_front_merge(struct request_queue *q, struct request *rq);
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void blk_recalc_rq_segments(struct request *rq);
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void blk_recalc_rq_sectors(struct request *rq, int nsect);
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void blk_queue_congestion_threshold(struct request_queue *q);
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int blk_dev_init(void);
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/*
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* Return the threshold (number of used requests) at which the queue is
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* considered to be congested. It include a little hysteresis to keep the
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* context switch rate down.
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*/
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static inline int queue_congestion_on_threshold(struct request_queue *q)
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{
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return q->nr_congestion_on;
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}
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/*
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* The threshold at which a queue is considered to be uncongested
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*/
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static inline int queue_congestion_off_threshold(struct request_queue *q)
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{
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return q->nr_congestion_off;
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}
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#if defined(CONFIG_BLK_DEV_INTEGRITY)
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#define rq_for_each_integrity_segment(bvl, _rq, _iter) \
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__rq_for_each_bio(_iter.bio, _rq) \
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bip_for_each_vec(bvl, _iter.bio->bi_integrity, _iter.i)
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#endif /* BLK_DEV_INTEGRITY */
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static inline int blk_cpu_to_group(int cpu)
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{
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#ifdef CONFIG_SCHED_MC
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cpumask_t mask = cpu_coregroup_map(cpu);
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return first_cpu(mask);
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#elif defined(CONFIG_SCHED_SMT)
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return first_cpu(per_cpu(cpu_sibling_map, cpu));
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#else
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return cpu;
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#endif
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}
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#endif
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