在 2022/09/14 14:05, Holger Hoffstätte 写道:
On 2022-09-14 03:35, Yu Kuai wrote:
[snip]
Thanks for the test, it turns out this way doesn't select bfq as default
as I expected...
wbt can show min_lat_nsec despite that wbt can be disabled by
wbt_disable_default(), I do miss that previously...
Can you try the following patch again?
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index a630d657c054..3e8adb95ff02 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -467,10 +467,14 @@ static ssize_t queue_io_timeout_store(struct
request_queue *q, const char *page,
static ssize_t queue_wb_lat_show(struct request_queue *q, char *page)
{
+ u64 lat;
+
if (!wbt_rq_qos(q))
return -EINVAL;
- return sprintf(page, "%llu\n", div_u64(wbt_get_min_lat(q),
1000));
+ lat = wbt_disabled(q) ? 0 : div_u64(wbt_get_min_lat(q), 1000);
+
+ return sprintf(page, "%llu\n", lat);
}
static ssize_t queue_wb_lat_store(struct request_queue *q, const
char *page,
@@ -493,6 +497,9 @@ static ssize_t queue_wb_lat_store(struct
request_queue *q, const char *page,
return ret;
}
+ if (wbt_disabled(q))
+ return -EINVAL;
+
if (val == -1)
val = wbt_default_latency_nsec(q);
else if (val >= 0)
diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index 26ee6ca66a93..55d1015ef117 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -423,6 +423,13 @@ static void wbt_update_limits(struct rq_wb *rwb)
rwb_wake_all(rwb);
}
+bool wbt_disabled(struct request_queue *q)
+{
+ struct rq_qos *rqos = wbt_rq_qos(q);
+
+ return !rqos || RQWB(rqos)->enable_state ==
WBT_STATE_OFF_DEFAULT;
+}
+
u64 wbt_get_min_lat(struct request_queue *q)
{
struct rq_qos *rqos = wbt_rq_qos(q);
diff --git a/block/blk-wbt.h b/block/blk-wbt.h
index 1a49b6ac397c..4252b8077257 100644
--- a/block/blk-wbt.h
+++ b/block/blk-wbt.h
@@ -94,6 +94,7 @@ void wbt_enable_default(struct request_queue *, bool);
u64 wbt_get_min_lat(struct request_queue *q);
void wbt_set_min_lat(struct request_queue *q, u64 val);
+bool wbt_disabled(struct request_queue *);
void wbt_set_write_cache(struct request_queue *, bool);
This one works! :)
After boot:
$cat /sys/block/sdc/queue/scheduler
mq-deadline [bfq] none
$cat /sys/block/sdc/queue/wbt_lat_usec
0
Changing schedulers back and forth - here on a device with different
default - also works:
$cat /sys/block/sda/queue/scheduler
[mq-deadline] bfq none
$cat /sys/block/sda/queue/wbt_lat_usec
2000
$echo bfq > /sys/block/sda/queue/scheduler
$cat /sys/block/sda/queue/wbt_lat_usec
0
$echo deadline > /sys/block/sda/queue/scheduler
$cat /sys/block/sda/queue/wbt_lat_usec
2000
Feel free to add my Reported-by and Tested-by.
I'll send a patch soon. Thanks again for the test.
Kuai
cheers!
Holger
.