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From: Josef Bacik <josef@toxicpanda.com>
To: Christopher Price <pricechrispy@gmail.com>
Cc: slyich@gmail.com, anand.jain@oracle.com, boris@bur.io,
	clm@fb.com,  dsterba@suse.com, linux-btrfs@vger.kernel.org,
	regressions@leemhuis.info,  regressions@lists.linux.dev
Subject: Re: [6.2 regression][bisected]discard storm on idle since v6.1-rc8-59-g63a7cb130718 discard=async
Date: Tue, 21 Mar 2023 17:26:49 -0400	[thread overview]
Message-ID: <CAEzrpqeOAiYCeHCuU2O8Hg5=xMwW_Suw1sXZtQ=f0f0WWHe9aw@mail.gmail.com> (raw)
In-Reply-To: <CAHmG9huwQcQXvy3HS0OP9bKFxwUa3aQj9MXZCr74emn0U+efqQ@mail.gmail.com>

On Mon, Mar 20, 2023 at 6:41 PM Christopher Price
<pricechrispy@gmail.com> wrote:
>
> I can also confirm the issue occurred on and after kernel 6.2, and
> confirm the workaround setting btrfs discard iops_limit works for my
> device:
>
> 08:00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd
> NVMe SSD Controller PM9A1/PM9A3/9
> 80PRO
>
> I had to use ~6000 for my device, instead of 1000.
> I'm currently on kernel 6.2.1.
>
> I am also interested to know what if this is expected.

We got the defaults based on our testing with our workloads inside of
FB.  Clearly this isn't representative of a normal desktop usage, but
we've also got a lot of workloads so figured if it made the whole
fleet happy it would probably be fine everywhere.

That being said this is tunable for a reason, your workload seems to
generate a lot of free'd extents and discards.  We can probably mess
with the async stuff to maybe pause discarding if there's no other
activity happening on the device at the moment, but tuning it to let
more discards through at a time is also completely valid.  Thanks,

Josef

  reply	other threads:[~2023-03-21 21:27 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-20 22:40 [6.2 regression][bisected]discard storm on idle since v6.1-rc8-59-g63a7cb130718 discard=async Christopher Price
2023-03-21 21:26 ` Josef Bacik [this message]
2023-03-22  8:38   ` Christoph Hellwig
2023-03-23 22:26     ` Sergei Trofimovich
2023-04-04 10:49       ` Linux regression tracking (Thorsten Leemhuis)
2023-04-04 16:04         ` Christoph Hellwig
2023-04-04 16:20           ` Roman Mamedov
2023-04-04 16:27             ` Christoph Hellwig
2023-04-04 23:37               ` Damien Le Moal
2023-04-04 18:15           ` Chris Mason
2023-04-04 18:51             ` Boris Burkov
2023-04-04 19:22               ` David Sterba
2023-04-04 19:39                 ` Boris Burkov
2023-04-05  8:17                   ` Linux regression tracking (Thorsten Leemhuis)
2023-04-10  2:03               ` Michael Bromilow
2023-04-11 17:52                 ` David Sterba
2023-04-11 18:15                   ` Linux regression tracking (Thorsten Leemhuis)
2023-04-04 19:08             ` Sergei Trofimovich
2023-04-05  6:18             ` Christoph Hellwig
2023-04-05 12:01               ` Chris Mason
2023-04-04 18:23         ` Boris Burkov
2023-04-04 19:12           ` Sergei Trofimovich
     [not found] <Y/+n1wS/4XAH7X1p@nz>
2023-03-02  8:04 ` Linux regression tracking #adding (Thorsten Leemhuis)
2023-04-04 10:52   ` Linux regression tracking #update (Thorsten Leemhuis)
2023-04-21 13:56   ` Linux regression tracking #update (Thorsten Leemhuis)
     [not found] ` <94cf49d0-fa2d-cc2c-240e-222706d69eb3@oracle.com>
     [not found]   ` <20230302105406.2cd367f7@nz>
2023-03-15 11:44     ` Linux regression tracking (Thorsten Leemhuis)
2023-03-15 16:34       ` Sergei Trofimovich

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