On 10/11/22 08:15, Jaroslav Pulchart wrote:
čt 6. 10. 2022 v 18:57 odesílatel Bart Van Assche <bvanassche@xxxxxxx> napsal:
On 10/6/22 05:36, Jaroslav Pulchart wrote:
I apply the
echo 0 > /sys/block/vdc/queue/wbt_lat_usec
at the production servers. I expect it will disable wbt. Could you
please confirm that my expectation is correct?
Hi Jaroslav,
I have no experience with WBT. But what I found in the documentation seems
to confirm that the above command is sufficient to disable WBT:
What: /sys/block/<disk>/queue/wbt_lat_usec
Date: November 2016
Contact: linux-block@xxxxxxxxxxxxxxx
Description:
[RW] If the device is registered for writeback throttling, then
this file shows the target minimum read latency. If this latency
is exceeded in a given window of time (see wb_window_usec), then
the writeback throttling will start scaling back writes. Writing
a value of '0' to this file disables the feature. Writing a
value of '-1' to this file resets the value to the default
setting.
>
> we disabled the wbt, issue is happening much sooner. The logs are attached
> 1/ "dmesg-20221011.log" form kernel messages
> 2/ "command.logs" from execution of
> (cd /sys/kernel/debug/block/vdc && find . -type f -exec grep -aH . {} \;)
>
> Best regards,
> Jaroslav Pulchart
(+Ted)
Hi Jaroslav,
Please reply at the bottom of an email when posting on a Linux kernel mailing
list (see also https://en.wikipedia.org/wiki/Posting_style#Bottom-posting).
Hi Ted,
In the dmesg fragment provided by Jaroslav I only see references to ext4. Are
you perhaps aware of any recently introduced issues in the layers between ext4
and the block layer? For the attachment provided by Jaroslav, see also
https://lore.kernel.org/linux-block/CAK8fFZ6ruxHsXuGT4qarNxdLLQtAoLsSvV0buFQhdc+TKo3Tag@xxxxxxxxxxxxxx/T/#m97ece301ca9a47ee8a4976f6c35ffcf55669b248
Thank you,
Bart.
