Christoph Hellwig [off-list ref] 于2020年3月31日周二 下午4:25写道：

On Fri, Mar 27, 2020 at 02:28:59PM +0800, Weiping Zhang wrote:

quoted

Change-Id: Ibb9caf20616f83e111113ab5c824c05930c0e523
Signed-off-by: Weiping Zhang <redacted>

This needs a commit description and loose the weird change id.

OK, I rewirte commit description, it record the timestamp of issue bio
to the disk driver,
then we can get the delta time in rq_qos_done_bio. It's same as the D2C time
of blktrace.

I also think oyu need to fins a way to not bloat the bio even more,
cgroup is a really bad offender for bio size.

struct request {
    u64 io_start_time_ns;
also record this timestamp, I'll check if we can use it.

Thanks a lot