On 26/03/17 05:18, [email protected] wrote:
From: Stephen Bates <[email protected]> In order to bucket IO for the polling algorithm we use a sysfs entry to set the filter value. It is signed and we will use that as follows: 0 : No filtering. All IO are considered in stat generation > 0 : Filtering based on IO of exactly this size only. < 0 : Filtering based on IO less than or equal to -1 time this value.
I'd say that this is a fairly non-trivial semantic meanning to this... Is there any use for the size exact match filter? If not then I suggest we always make it (<=) in its semantics...
Use this member to implement a new bucket function for the io polling stats. Signed-off-by: Stephen Bates <[email protected]> --- block/blk-mq.c | 17 +++++++++++++++-- block/blk-sysfs.c | 30 ++++++++++++++++++++++++++++++ include/linux/blkdev.h | 1 + 3 files changed, 46 insertions(+), 2 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 5ff66f2..5ea9481 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2327,6 +2327,18 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set, blk_mq_sysfs_register(q); } +int blk_mq_poll_stats_bucket(const struct request *rq) +{ + int val = rq->q->poll_size; + + if ((val == 0) || + (val > 0 && blk_rq_bytes(rq) == val) || + (val < 0 && blk_rq_bytes(rq) <= -val)) + return (int)rq_data_dir(rq); + + return -1; +} + struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set, struct request_queue *q) { @@ -2338,7 +2350,7 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set, goto err_exit; q->poll_cb = blk_stat_alloc_callback(blk_mq_poll_stats_fn, - blk_stat_rq_ddir, 2, q); + blk_mq_poll_stats_bucket, 2, q); if (!q->poll_cb) goto err_exit; @@ -2387,9 +2399,10 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set, q->nr_requests = set->queue_depth; /* - * Default to classic polling + * Default to classic polling. Default to considering all IO. */ q->poll_nsec = -1; + q->poll_size = 0; if (set->ops->complete) blk_queue_softirq_done(q, set->ops->complete); diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index fa831cb..000d5db 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -394,6 +394,29 @@ static ssize_t queue_poll_delay_store(struct request_queue *q, const char *page, return count; } +static ssize_t queue_poll_size_show(struct request_queue *q, char *page) +{ + return sprintf(page, "%d\n", q->poll_size); +} + +static ssize_t queue_poll_size_store(struct request_queue *q, const char *page, + size_t count) +{ + int err, val; + + if (!q->mq_ops || !q->mq_ops->poll) + return -EINVAL; + + err = kstrtoint(page, 10, &val); + if (err < 0) + return err; + + q->poll_size = val; + + return count; +} + + static ssize_t queue_poll_show(struct request_queue *q, char *page) { return queue_var_show(test_bit(QUEUE_FLAG_POLL, &q->queue_flags), page); @@ -654,6 +677,12 @@ static struct queue_sysfs_entry queue_poll_entry = { .store = queue_poll_store, }; +static struct queue_sysfs_entry queue_poll_size_entry = { + .attr = {.name = "io_poll_size", .mode = S_IRUGO | S_IWUSR }, + .show = queue_poll_size_show, + .store = queue_poll_size_store, +}; + static struct queue_sysfs_entry queue_poll_delay_entry = { .attr = {.name = "io_poll_delay", .mode = S_IRUGO | S_IWUSR }, .show = queue_poll_delay_show, @@ -710,6 +739,7 @@ static struct attribute *default_attrs[] = { &queue_dax_entry.attr, &queue_wb_lat_entry.attr, &queue_poll_delay_entry.attr, + &queue_poll_size_entry.attr, NULL, }; diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 1a7dc42..7ff5388 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -517,6 +517,7 @@ struct request_queue { unsigned int rq_timeout; int poll_nsec; + int poll_size; struct blk_stat_callback *poll_cb; struct blk_rq_stat poll_stat[2];
