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authorJens Axboe <axboe@kernel.dk>2017-06-16 10:59:45 -0600
committerJens Axboe <axboe@fb.com>2017-06-17 13:54:15 -0600
commit6e001309d91902c1749455327c7aedd4ab6c11a0 (patch)
treeabef954a7f3933bf3508fe8d98adf5e318bf1b40
parenta0311a8e50b6247753801a24a82c08129b073ad8 (diff)
blk-mq: expose stream write hints through debugfs
Useful to verify that things are working the way they should. Reading the file will return number of kb written with each write hint. Writing the file will reset the statistics. No care is taken to ensure that we don't race on updates. Drivers will write to q->write_hints[] if they handle a given write hint. Reviewed-by: Andreas Dilger <adilger@dilger.ca> Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--block/blk-mq-debugfs.c24
-rw-r--r--include/linux/blkdev.h3
2 files changed, 27 insertions, 0 deletions
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 803aed4d7221..b069a76f7fc7 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -133,6 +133,29 @@ static void print_stat(struct seq_file *m, struct blk_rq_stat *stat)
}
}
+static int queue_write_hint_show(void *data, struct seq_file *m)
+{
+ struct request_queue *q = data;
+ int i;
+
+ for (i = 0; i < BLK_MAX_WRITE_HINTS; i++)
+ seq_printf(m, "hint%d: %llu\n", i, q->write_hints[i]);
+
+ return 0;
+}
+
+static ssize_t queue_write_hint_store(void *data, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct request_queue *q = data;
+ int i;
+
+ for (i = 0; i < BLK_MAX_WRITE_HINTS; i++)
+ q->write_hints[i] = 0;
+
+ return count;
+}
+
static int queue_poll_stat_show(void *data, struct seq_file *m)
{
struct request_queue *q = data;
@@ -656,6 +679,7 @@ const struct file_operations blk_mq_debugfs_fops = {
static const struct blk_mq_debugfs_attr blk_mq_debugfs_queue_attrs[] = {
{"poll_stat", 0400, queue_poll_stat_show},
{"state", 0600, queue_state_show, queue_state_write},
+ {"write_hints", 0600, queue_write_hint_show, queue_write_hint_store},
{},
};
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index b74a3edcb3da..ab36068f6129 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -588,6 +588,9 @@ struct request_queue {
void *rq_alloc_data;
struct work_struct release_work;
+
+#define BLK_MAX_WRITE_HINTS 5
+ u64 write_hints[BLK_MAX_WRITE_HINTS];
};
#define QUEUE_FLAG_QUEUED 1 /* uses generic tag queueing */