APPLIED(B,C): [SRU] [B/C] [PATCH 0/2] Fix for LP: #1815733

Khaled Elmously khalid.elmously at canonical.com
Tue May 7 04:21:14 UTC 2019


On 2019-04-24 18:23:28 , Kai-Heng Feng wrote:
> BugLink: https://bugs.launchpad.net/bugs/1815733
> 
> [Impact]
> Quote from the bug description:
> "
> This behavior affects production systems, because every change uevent
> triggers udev to change settings prior to udev rules. Some software, for
> example arcconf (tool for managing adaptec HBA adapters) triggers
> uevents for every block device. So, every call to arcconf utility
> results in latency spike.
> "
> 
> [Fix]
> Avoid unnecessary queue freeze in either one of the case:
>  - the queue depth is about to be set to the same value, or 
>  - scheduler is "none" and is about to be set to "none" again.
> 
> [Test]
> The user confirm these two patches works.
> 
> [Regression Potential]
> Low. The fix has been in Disco for a while, should be safe to backport
> to older releases.
> 
> Aleksei Zakharov (2):
>   block: avoid setting nr_requests to current value
>   block: avoid setting none scheduler if it's already none
> 
>  block/blk-mq.c   | 3 +++
>  block/elevator.c | 3 +++
>  2 files changed, 6 insertions(+)
> 
> -- 
> 2.17.1
> 
> 
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