From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: Keith Busch <keith.busch@intel.com>
Cc: Ric Wheeler <ricwheeler@gmail.com>,
Dave Chinner <david@fromorbit.com>,
lsf-pc@lists.linux-foundation.org,
linux-xfs <linux-xfs@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-ext4 <linux-ext4@vger.kernel.org>,
linux-btrfs <linux-btrfs@vger.kernel.org>,
linux-block@vger.kernel.org
Subject: Re: [LSF/MM TOPIC] More async operations for file systems - async discard?
Date: Thu, 21 Feb 2019 21:51:12 -0500 [thread overview]
Message-ID: <yq18sy8ili7.fsf@oracle.com> (raw)
In-Reply-To: <20190220234723.GA5999@localhost.localdomain> (Keith Busch's message of "Wed, 20 Feb 2019 16:47:24 -0700")
Keith,
> With respect to fs block sizes, one thing making discards suck is that
> many high capacity SSDs' physical page sizes are larger than the fs
> block size, and a sub-page discard is worse than doing nothing.
That ties into the whole zeroing as a side-effect thing.
The devices really need to distinguish between discard-as-a-hint where
it is free to ignore anything that's not a whole multiple of whatever
the internal granularity is, and the WRITE ZEROES use case where the end
result needs to be deterministic.
--
Martin K. Petersen Oracle Linux Engineering
next prev parent reply other threads:[~2019-02-22 2:51 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-17 20:36 [LSF/MM TOPIC] More async operations for file systems - async discard? Ric Wheeler
2019-02-17 21:09 ` Dave Chinner
2019-02-17 23:42 ` Ric Wheeler
2019-02-18 2:22 ` Dave Chinner
2019-02-18 22:30 ` Ric Wheeler
2019-02-20 23:47 ` Keith Busch
2019-02-21 20:08 ` Dave Chinner
2019-02-21 23:55 ` Jeff Mahoney
2019-02-22 3:01 ` Martin K. Petersen
2019-02-22 6:15 ` Roman Mamedov
2019-02-22 14:12 ` Martin K. Petersen
2019-02-22 2:51 ` Martin K. Petersen [this message]
2019-02-22 16:45 ` Keith Busch
2019-02-27 11:40 ` Ric Wheeler
2019-02-27 13:24 ` Matthew Wilcox
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