Hi,

On 3/17/21 6:56 PM, Matthias Schwarzott wrote:

Am 17.03.21 um 16:17 schrieb Alan Stern:

quoted

On Wed, Mar 17, 2021 at 01:21:50PM +0100, Hans de Goede wrote:

quoted

Hi,

On 3/16/21 6:04 PM, Alan Stern wrote:

quoted

I think it would be mildly better, but not a whole lot.  Since the
Kindle describes itself as having removable media, the kernel normally
probes it periodically to make sure the media remains present.  The
default probing interval is 2 seconds.  Reducing it to 0.9 seconds
doesn't represent an exorbitant additional load IMO -- especially since
Kindles don't tend to spend huge amounts of time connected to computers.

Ah, I did not know that the default polling interval was that low(ish),
given that the default indeed is already that low, then changing it to
0.8 seconds would not be a big change.  And we probably have a lot of
lower hanging fruit for unnecessary wakeups then that.

So we need to make a decision: Should the patch be merged, or should we
punt the issue to userspace tools?

On the plus side, the patch is rather small and non-invasive (although
it does allocate the last remaining bit in the 32-bit fflags field).
There's also the advantage of sending the extra command only when it is
needed, as opposed to increasing the overall frequency of TUR polling.

Any opinions?

I would vote to do in kernel as that is a cleaner solution:

1. It will work out of the box.
2. It only sends one extra command when needed.
3. It makes the block-device not break if user-space adjusts the poll interval to higher values.

FWIW my vote goes to the in kernel fix too.

Regards,

Hans