From: Lukas Czerner <lczerner@redhat.com>
To: Theodore Ts'o <tytso@mit.edu>
Cc: Ext4 Developers List <linux-ext4@vger.kernel.org>,
darrick.wong@oracle.com
Subject: Re: [PATCH 8/9] e2scrub_all: refactor device probe loop
Date: Thu, 21 Mar 2019 22:14:37 +0100 [thread overview]
Message-ID: <20190321211437.qdbvjmbwaaji3id6@work> (raw)
In-Reply-To: <20190321204823.GJ9434@mit.edu>
On Thu, Mar 21, 2019 at 04:48:23PM -0400, Theodore Ts'o wrote:
> On Thu, Mar 21, 2019 at 09:17:10PM +0100, Lukas Czerner wrote:
> >
> > Right, I did mention it later in the reply. It can be filtered
> >
> > grep -v '^/dev/'
>
> Well, that assumes all device nodes are in /dev. Which is not
> necessarily always the case, especially in some of the more _whacky_
> container setups which I've seen. (Hmm, is whacky redundant here?)
Fair enough, I've never seen this outside dm/lvm testing.
>
> I suppose can test whether or not the path is a block device or a
> directory.....
>
> >
> > For me this new function is the wors of all.
> >
> > cold cache:
> > real 0m2.115s
> > user 0m0.040s
> > sys 0m0.154s
> >
> > second time:
> > real 0m1.100s
> > user 0m0.037s
> > sys 0m0.122s
> >
> > But that's because of blkid which is terribly slow for some reason.
>
> I ran my test on a system with a NVMe SSD, and no HDD's attached. I
> just did an strace, and I see the util-linux folks have really done a
> great job of pessimizing blkid. :-(
Yeah, all I have on that system is spinning rust :)
lsblk works good enough for me so I am not sure how I feel about special
binary to check the mount point :)
-Lukas
>
> My version used to just pull the information from the blkid cache file
> and then verified the results, but it looks like the new, improved
> util-linux version of blkid scans the /dev directory and opens and
> reads from each device node, even when we're querying a single block
> device. <groan>
>
> Even lsblk is *amazingly* inefficient in terms of the number of
> useless file opens which it performs, although at least they are all
> /sysfs files.
>
> I'm half tempted to create and ship a binary which just calls
> ext2fs_check_mount_point() and returns the value, since it's the most
> efficient. This command
>
> sudo strace -o /tmp/st /build/e2fsprogs-maint/lib/ext2fs/tst_ismounted /dev/lambda/tp
>
> Opens /proc/mounts and does a trial mount of /dev/lambda/tp to make
> sure it's actually busy, and that's it.
>
> Sigh...
>
> - Ted
next prev parent reply other threads:[~2019-03-21 21:14 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-21 2:02 [PATCH 1/9] e2scrub: check to make sure lvm2 is installed Theodore Ts'o
2019-03-21 2:02 ` [PATCH 2/9] debian: drop lvm2 from the recommends line Theodore Ts'o
2019-03-21 3:57 ` Darrick J. Wong
2019-03-21 2:02 ` [PATCH 3/9] Fix "make install-strip" Theodore Ts'o
2019-03-21 2:02 ` [PATCH 4/9] e2scrub: fix up "make install-strip" support Theodore Ts'o
2019-03-21 2:02 ` [PATCH 5/9] e2fscrub: add the -n option which shows what commands e2scrub would execute Theodore Ts'o
2019-03-21 3:59 ` Darrick J. Wong
2019-03-21 10:57 ` Lukas Czerner
2019-03-21 14:32 ` Theodore Ts'o
2019-03-21 2:02 ` [PATCH 6/9] e2scrub_all: add the -n option which shows what e2scrub_all would do Theodore Ts'o
2019-03-21 4:01 ` Darrick J. Wong
2019-03-21 2:02 ` [PATCH 7/9] e2scrub_all: make sure there's enough free space for a snapshot Theodore Ts'o
2019-03-21 4:02 ` Darrick J. Wong
2019-03-21 11:18 ` Lukas Czerner
2019-03-21 14:26 ` Theodore Ts'o
2019-03-21 2:02 ` [PATCH 8/9] e2scrub_all: refactor device probe loop Theodore Ts'o
2019-03-21 4:05 ` Darrick J. Wong
2019-03-21 10:27 ` Lukas Czerner
2019-03-21 14:31 ` Theodore Ts'o
2019-03-21 15:57 ` Lukas Czerner
2019-03-21 18:24 ` Theodore Ts'o
2019-03-21 20:17 ` Lukas Czerner
2019-03-21 20:48 ` Theodore Ts'o
2019-03-21 21:14 ` Lukas Czerner [this message]
2019-03-21 22:04 ` Theodore Ts'o
2019-03-21 22:08 ` Theodore Ts'o
2019-03-22 9:38 ` Lukas Czerner
2019-03-21 20:09 ` Andreas Dilger
2019-03-21 17:48 ` Theodore Ts'o
2019-03-21 19:49 ` Lukas Czerner
2019-03-21 20:23 ` Theodore Ts'o
2019-03-21 16:10 ` Lukas Czerner
2019-03-21 2:02 ` [PATCH 9/9] e2scrub,e2scrub_all: print a (more understandable) error if not run as root Theodore Ts'o
2019-03-21 4:04 ` Darrick J. Wong
2019-03-21 11:36 ` Lukas Czerner
2019-03-21 14:40 ` Theodore Ts'o
2019-03-21 3:55 ` [PATCH 1/9] e2scrub: check to make sure lvm2 is installed Darrick J. Wong
-- strict thread matches above, loose matches on Subject: below --
2019-03-21 20:25 [PATCH -v2 0/9] e2fsprogs: e2scrub cleanups Theodore Ts'o
2019-03-21 20:25 ` [PATCH 8/9] e2scrub_all: refactor device probe loop Theodore Ts'o
2019-03-21 20:55 ` Lukas Czerner
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190321211437.qdbvjmbwaaji3id6@work \
--to=lczerner@redhat.com \
--cc=darrick.wong@oracle.com \
--cc=linux-ext4@vger.kernel.org \
--cc=tytso@mit.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox