From: "Darrick J. Wong" <djwong@kernel.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Andreas Dilger <adilger@dilger.ca>,
Josh Triplett <josh@joshtriplett.org>,
David Howells <dhowells@redhat.com>,
Theodore Ts'o <tytso@mit.edu>, Chris Mason <clm@fb.com>,
Ext4 Developers List <linux-ext4@vger.kernel.org>,
xfs <linux-xfs@vger.kernel.org>,
linux-btrfs <linux-btrfs@vger.kernel.org>,
linux-cachefs@redhat.com,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
NeilBrown <neilb@suse.com>
Subject: Re: How capacious and well-indexed are ext4, xfs and btrfs directories?
Date: Tue, 25 May 2021 15:13:51 -0700 [thread overview]
Message-ID: <20210525221351.GB202068@locust> (raw)
In-Reply-To: <YK1rebI5vZKCeLlp@casper.infradead.org>
On Tue, May 25, 2021 at 10:26:17PM +0100, Matthew Wilcox wrote:
> On Tue, May 25, 2021 at 03:13:52PM -0600, Andreas Dilger wrote:
> > Definitely "-o discard" is known to have a measurable performance impact,
> > simply because it ends up sending a lot more requests to the block device,
> > and those requests can be slow/block the queue, depending on underlying
> > storage behavior.
> >
> > There was a patch pushed recently that targets "-o discard" performance:
> > https://patchwork.ozlabs.org/project/linux-ext4/list/?series=244091
> > that needs a bit more work, but may be worthwhile to test if it improves
> > your workload, and help put some weight behind landing it?
>
> This all seems very complicated. I have chosen with my current laptop
> to "short stroke" the drive. That is, I discarded the entire bdev,
> then partitioned it roughly in half. The second half has never seen
> any writes. This effectively achieves the purpose of TRIM/discard;
> there are a lot of unused LBAs, so the underlying flash translation layer
> always has plenty of spare space when it needs to empty an erase block.
>
> Since the steady state of hard drives is full, I have to type 'make clean'
> in my build trees more often than otherwise and remember to delete iso
> images after i've had them lying around for a year, but I'd rather clean
> up a little more often than get these weird performance glitches.
>
> And if I really do need half a terabyte of space temporarily, I can
> always choose to use the fallow range for a while, then discard it again.
I just let xfs_scrub run FITRIM on Sundays at 4:30am. ;)
--D
next prev parent reply other threads:[~2021-05-25 22:13 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-17 15:06 How capacious and well-indexed are ext4, xfs and btrfs directories? David Howells
2021-05-17 23:22 ` Dave Chinner
2021-05-17 23:40 ` Chris Mason
2021-05-19 8:00 ` Avi Kivity
2021-05-19 12:57 ` Dave Chinner
2021-05-19 14:13 ` Avi Kivity
2021-05-18 7:24 ` David Howells
2021-05-21 5:13 ` Andreas Dilger
2021-05-23 5:51 ` Josh Triplett
2021-05-25 4:21 ` Darrick J. Wong
2021-05-25 5:00 ` Christoph Hellwig
2021-05-25 21:13 ` Andreas Dilger
2021-05-25 21:26 ` Matthew Wilcox
2021-05-25 22:13 ` Darrick J. Wong [this message]
2021-05-25 22:48 ` Andreas Dilger
2021-05-26 0:24 ` Chris Mason
2021-06-22 0:50 ` Josh Triplett
2021-05-25 22:31 ` David Howells
2021-05-25 22:58 ` Andreas Dilger
2021-05-26 0:00 ` David Howells
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