On 26/03/17 05:18, sbates@xxxxxxxxxxxx wrote:
From: Stephen Bates <sbates@xxxxxxxxxxxx>
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 <sbates@xxxxxxxxxxxx>
---
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];
