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From: David Sterba <dsterba@suse.cz>
To: Neal Gompa <ngompa13@gmail.com>
Cc: Btrfs BTRFS <linux-btrfs@vger.kernel.org>,
	Chris Mason <clm@fb.com>, Josef Bacik <josef@toxicpanda.com>,
	Chris Murphy <lists@colorremedies.com>
Subject: Re: Using async discard by default with SSDs?
Date: Mon, 25 Jul 2022 21:08:11 +0200	[thread overview]
Message-ID: <20220725190811.GD13489@twin.jikos.cz> (raw)
In-Reply-To: <CAEg-Je_b1YtdsCR0zS5XZ_SbvJgN70ezwvRwLiCZgDGLbeMB=w@mail.gmail.com>

On Thu, Jul 21, 2022 at 02:43:16PM -0400, Neal Gompa wrote:
> Hey all,
> 
> I was talking with Chris Mason today at a Fedora Hatch event about
> async discards (as we were thinking about doing this in Fedora some
> time ago[1]), and he seemed to consider it reasonable to make it so
> Btrfs uses async discards by default when being formatted on SSDs.
> 
> He and I couldn't think of a reason why not to, other than the
> potential lack of "discard=none" option to turn off discards if the
> user wanted it to. Do we already have this option? Are there any other
> reasons not to do this? Or is this something we should have changed in
> Btrfs so everyone gets async discards by default going forward?

I think it's safe to use by default, with the usual question who could
be affected by that negatively. The async triggers, timeouts and
thresholds are preset conservatively and so far there have been no
complaints.

The tunables have been hidden under debug, but there are also some stats
(like how many bytes could be discarded in the next round), so it would
be good to also publish that when it's on by default.

  parent reply	other threads:[~2022-07-25 19:13 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-21 18:43 Using async discard by default with SSDs? Neal Gompa
2022-07-21 19:21 ` Roman Mamedov
2022-07-25 19:08 ` David Sterba [this message]
2022-07-26 20:00   ` Chris Murphy
2022-07-26 21:36     ` David Sterba
2022-07-26 22:10       ` Chris Murphy
2022-07-27 14:50         ` Chris Murphy
2022-07-27 14:56           ` David Sterba
2022-07-27 15:14             ` Chris Murphy
2022-07-27 17:47               ` David Sterba
2022-07-28 12:27                 ` Chris Murphy
2022-07-27 15:26             ` Neal Gompa
2022-08-05 15:14             ` David Sterba

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