Re: [RFC PATCH v2 00/10] Add configurable block device LED triggers
From: Marek Behún
Date: Mon Aug 09 2021 - 14:56:55 EST
Hello Ian,
thank you for your proposal. Some comments below:
On Sun, 8 Aug 2021 22:32:07 -0500
Ian Pilcher <arequipeno@xxxxxxxxx> wrote:
> One thing that has not changed is that associations between block
> devices and LEDs are still set via an attribute on the device, rather
> than the LED. This is much simpler, as the device attribute only has
> to handle a single value (the name of the associated LED), rather than
> potentially handling multiple device names.
It may be simpler, but it is in contrast to how the netdev trigger
works, which already is in upstream for many years. I really think we
should try to have similar sysfs ABIs here. (I understand that the
netdev trigger is currently unable to handle multiple network
interfaces - but it is possible to extend it so.)
> I have modeled the interface for the /sys/block/<DEVICE>/led
> attribute on the sysfs interface used for selecting a trigger. All
> available LEDs (all LEDs associated with the blkdev trigger) are
> shown when the attribute is read, with the currently selected LED
> enclosed in square brackets ([]).
I think it is reasonable to be able to set something like this:
led0 : blink on activity on any of [sda, sdb, sdc]
led1 : blink on activity on sda
led2 : blink on activity on sdb
led3 : blink on activity on sdc
If I am reading your code correctly, it looks that only one LED can be
configured for a block device. Is this true? If so, then the above
configuration cannot be set.
Also you are blinking the LED on any request to the block device. I
would rather expect to be able to set the LED to blink on read and on
write. (And possibly on other functions, like discard, or critical
temperature, or error, ...) I would like to know what other people
think about this.
Marek