We apply a smoothing to the scale changes in order to keep sawtoothy
behavior from occurring. However our window for checking if we've
missed our target can sometimes be lower than the smoothing interval
(500ms), especially on faster drives like ssd's. In order to deal with
this keep track of
We use an average latency approach for determining if we're missing our
latency target. This works well for rotational storage where we have
generally consistent latencies, but for ssd's and other low latency
devices you have more of a spikey behavior, which means we often won't
throttle
There is logic to keep cgroups that haven't done a lot of IO in the most
recent scale window from being punished for over-active higher priority
groups. However for things like ssd's where the windows are pretty
short we'll end up with small numbers of samples, so 5% of samples will
come out to 0
Hitting the case where blk_queue_depth() returned 1 uncovered the fact
that iolatency doesn't actually handle this case properly, it simply
doesn't scale down anybody. For this case we should go straight into
applying the time delay, which we weren't doing. Since we already limit
the floor at 1
This was from a previous iteration when we returned whether or not we
changed the scale. It is unused so remove it.
Signed-off-by: Josef Bacik
---
block/blk-iolatency.c | 3 ---
1 file changed, 3 deletions(-)
diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c
index
We were using blk_queue_depth() assuming that it would return
nr_requests, but we hit a case in production on drives that had to have
NCQ turned off in order for them to not shit the bed which resulted in a
qd of 1, even though the nr_requests was much larger. iolatency really
only cares about
On 9/10/18 12:02 AM, Christoph Hellwig wrote:
> The following changes since commit bc811f05d77f47059c197a98b6ad242eb03999cb:
>
> nbd: don't allow invalid blocksize settings (2018-09-04 11:54:58 -0600)
>
> are available in the Git repository at:
>
> git://git.infradead.org/nvme.git nvme-4.19
The following changes since commit bc811f05d77f47059c197a98b6ad242eb03999cb:
nbd: don't allow invalid blocksize settings (2018-09-04 11:54:58 -0600)
are available in the Git repository at:
git://git.infradead.org/nvme.git nvme-4.19
for you to fetch changes up to
