[prev in list] [next in list] [prev in thread] [next in thread] 

List:       fedora-devel-list
Subject:    Re: Fedora 32 System-Wide Change proposal: Enable fstrim.timer by default
From:       Chris Murphy <lists () colorremedies ! com>
Date:       2019-12-20 17:59:52
Message-ID: CAJCQCtQ2NOYwB-u+n9eYpatJonDz8Vz3=HA1ybpVrr+XHeGMrQ () mail ! gmail ! com
[Download RAW message or body]

On Fri, Dec 20, 2019 at 2:24 AM Lennart Poettering <mzerqung@0pointer.de> wrote:
>
> On Do, 19.12.19 16:42, Ben Cotton (bcotton@redhat.com) wrote:
>
> > Over time, some users experience slow downs in certain flash storage
> > devices. This might be alleviated by issuing a periodic fstrim command
> > to the mounted file system. Devices and file systems that don't
> > support fstrim are unaffected.
>
> So, if this is desirable, why doesn't the kernel do this on its own?

The simple answer is, because we're only just now coming out of the
stone age, and into the bronze age, of SSDs. There were too many
significant differences in early SSD behavior across makes/models. The
way that's been handled across platforms (Linux, macOS, Windows, BSD)
differs too, reflecting that the standards weren't specific enough,
ample vendor confusion and firmware bugs, etc. Today the supply of
SSDs is very heterogeneous, and they inadequately announce their
capabilities and preferences in this regard.

> Why do we need a userspace component that just gets an event from the
> kernel and then tells the kernel to do something? If this is generally
> desirable, why is something as trivial as that not a kernel
> functionality anyway?

Issuing the command once per week harms no one, and benefits a few who
happen to have devices that will perform better with this scheduled
hint than without it. It's the most universally applicable way of
doing it, however subjective. And as mentioned in the proposal, other
distributions have had this same unit enabled for many years.

It's reasonable to enable fstrim.timer now. *And* conduct parallel
development to create a kernel facility to do this automatically, if
it's even possible. I'm not convinced the drives report enough
information to do this properly automatically, rather than on a
schedule.

But saying this belongs in the kernel, indeterminate future, while
other distributions have been doing this on a schedule upwards of six
years, and is supported on Windows and macOS for about that long too?
*shrug* I'm not sure that makes sense. And to be true, Windows and
macOS have used their own white listing method to do this, meaning
quite a lot of devices aren't getting these hints and are left out.


-- 
Chris Murphy
_______________________________________________
devel mailing list -- devel@lists.fedoraproject.org
To unsubscribe send an email to devel-leave@lists.fedoraproject.org
Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/
List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines
List Archives: https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org

[prev in list] [next in list] [prev in thread] [next in thread]