diff options
| -rw-r--r-- | block/cfq-iosched.c | 79 |
1 files changed, 76 insertions, 3 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 5e01a0a92c0..47d6aaca0c5 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -38,6 +38,12 @@ static int cfq_slice_idle = HZ / 125; */ #define CFQ_MIN_TT (2) +/* + * Allow merged cfqqs to perform this amount of seeky I/O before + * deciding to break the queues up again. + */ +#define CFQQ_COOP_TOUT (HZ) + #define CFQ_SLICE_SCALE (5) #define CFQ_HW_QUEUE_MIN (5) @@ -116,6 +122,7 @@ struct cfq_queue { u64 seek_total; sector_t seek_mean; sector_t last_request_pos; + unsigned long seeky_start; pid_t pid; @@ -1036,6 +1043,11 @@ static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, { struct cfq_queue *cfqq; + if (!cfq_cfqq_sync(cur_cfqq)) + return NULL; + if (CFQQ_SEEKY(cur_cfqq)) + return NULL; + /* * We should notice if some of the queues are cooperating, eg * working closely on the same area of the disk. In that case, @@ -1050,6 +1062,8 @@ static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, */ if (!cfq_cfqq_sync(cfqq)) return NULL; + if (CFQQ_SEEKY(cfqq)) + return NULL; return cfqq; } @@ -1181,7 +1195,7 @@ static int cfqq_process_refs(struct cfq_queue *cfqq) static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) { - int process_refs; + int process_refs, new_process_refs; struct cfq_queue *__cfqq; /* Avoid a circular list and skip interim queue merges */ @@ -1199,8 +1213,17 @@ static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) if (process_refs == 0) return; - cfqq->new_cfqq = new_cfqq; - atomic_add(process_refs, &new_cfqq->ref); + /* + * Merge in the direction of the lesser amount of work. + */ + new_process_refs = cfqq_process_refs(new_cfqq); + if (new_process_refs >= process_refs) { + cfqq->new_cfqq = new_cfqq; + atomic_add(process_refs, &new_cfqq->ref); + } else { + new_cfqq->new_cfqq = cfqq; + atomic_add(new_process_refs, &cfqq->ref); + } } /* @@ -2029,6 +2052,19 @@ cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq, total = cfqq->seek_total + (cfqq->seek_samples/2); do_div(total, cfqq->seek_samples); cfqq->seek_mean = (sector_t)total; + + /* + * If this cfqq is shared between multiple processes, check to + * make sure that those processes are still issuing I/Os within + * the mean seek distance. If not, it may be time to break the + * queues apart again. + */ + if (cfq_cfqq_coop(cfqq)) { + if (CFQQ_SEEKY(cfqq) && !cfqq->seeky_start) + cfqq->seeky_start = jiffies; + else if (!CFQQ_SEEKY(cfqq)) + cfqq->seeky_start = 0; + } } /* @@ -2391,6 +2427,32 @@ cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic, return cic_to_cfqq(cic, 1); } +static int should_split_cfqq(struct cfq_queue *cfqq) +{ + if (cfqq->seeky_start && + time_after(jiffies, cfqq->seeky_start + CFQQ_COOP_TOUT)) + return 1; + return 0; +} + +/* + * Returns NULL if a new cfqq should be allocated, or the old cfqq if this + * was the last process referring to said cfqq. + */ +static struct cfq_queue * +split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq) +{ + if (cfqq_process_refs(cfqq) == 1) { + cfqq->seeky_start = 0; + cfqq->pid = current->pid; + cfq_clear_cfqq_coop(cfqq); + return cfqq; + } + + cic_set_cfqq(cic, NULL, 1); + cfq_put_queue(cfqq); + return NULL; +} /* * Allocate cfq data structures associated with this request. */ @@ -2413,12 +2475,23 @@ cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) if (!cic) goto queue_fail; +new_queue: cfqq = cic_to_cfqq(cic, is_sync); if (!cfqq || cfqq == &cfqd->oom_cfqq) { cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask); cic_set_cfqq(cic, cfqq, is_sync); } else { /* + * If the queue was seeky for too long, break it apart. + */ + if (cfq_cfqq_coop(cfqq) && should_split_cfqq(cfqq)) { + cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq"); + cfqq = split_cfqq(cic, cfqq); + if (!cfqq) + goto new_queue; + } + + /* * Check to see if this queue is scheduled to merge with * another, closely cooperating queue. The merging of * queues happens here as it must be done in process context. |