From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: John Pittman <jpittman@redhat.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>,
axboe@kernel.dk, djeffery@redhat.com, loberman@redhat.com,
emilne@redhat.com, minlei@redhat.com,
linux-block@vger.kernel.org
Subject: Re: [PATCH] block: set reasonable default for discard max
Date: Mon, 12 Jun 2023 20:55:46 -0400 [thread overview]
Message-ID: <yq14jnc18y0.fsf@ca-mkp.ca.oracle.com> (raw)
In-Reply-To: <CA+RJvhzPfmjD0FZxWS5gFeZJWKki5OcdmywZdngqhgSjm6wiFA@mail.gmail.com> (John Pittman's message of "Fri, 9 Jun 2023 20:22:31 -0400")
John,
> Thanks alot for responding Martin. Forgive my ignorance; just trying
> to gain understanding. For example, if we find a device with a 2TiB
> max discard (way too high for any device to handle reasonably from
> what I've seen),
That really depends. On some devices performing a 2TB discard may just
involve updating a few entries in a block translation table. It could be
close to constant time regardless of the number of terabytes unmapped.
> and we make a quirk for it that brings the max discard down, how do we
> decide what value to bring that down to? Would we ask the hardware
> vendor for an optimal value? Is there some way we could decide the
> value?
The best thing would be to ask the vendor. Or maybe if you provide the
output of
# sg_vpd -p bl /dev/sdN
and we can try to see if we can come up with a suitable heuristic for a
quirk.
--
Martin K. Petersen Oracle Linux Engineering
next prev parent reply other threads:[~2023-06-13 0:56 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-09 18:08 [PATCH] block: set reasonable default for discard max John Pittman
2023-06-09 18:46 ` Martin K. Petersen
2023-06-10 0:22 ` John Pittman
2023-06-10 22:52 ` Chaitanya Kulkarni
2023-06-13 0:55 ` Martin K. Petersen [this message]
2023-06-13 11:23 ` Ewan Milne
2023-06-13 1:37 ` Ming Lei
2023-06-19 16:02 ` John Pittman
2023-06-20 15:06 ` Martin K. Petersen
2023-07-14 17:15 ` John Pittman
2023-07-20 1:58 ` Martin K. Petersen
2023-07-20 14:43 ` John Pittman
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