From: "Theodore Ts'o" <tytso@mit.edu>
To: Sage Weil <sage@newdream.net>
Cc: Trond Myklebust <trond.myklebust@primarydata.com>,
Dave Chinner <david@fromorbit.com>, Zach Brown <zab@redhat.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux API Mailing List <linux-api@vger.kernel.org>
Subject: Re: [PATCH RFC] vfs: add a O_NOMTIME flag
Date: Mon, 11 May 2015 19:10:21 -0400 [thread overview]
Message-ID: <20150511231021.GC14088@thunk.org> (raw)
In-Reply-To: <alpine.DEB.2.00.1505110920520.28239@cobra.newdream.net>
On Mon, May 11, 2015 at 09:24:09AM -0700, Sage Weil wrote:
> > Let me re-ask the question that I asked last week (and was apparently
> > ignored). Why not trying to use the lazytime feature instead of
> > pointing a head straight at the application's --- and system
> > administrators' --- heads?
>
> Sorry Ted, I thought I responded already.
>
> The goal is to avoid inode writeout entirely when we can, and
> as I understand it lazytime will still force writeout before the inode
> is dropped from the cache. In systems like Ceph in particular, the
> IOs can be spread across lots of files, so simply deferring writeout
> doesn't always help.
Sure, but it would reduce the writeout by orders of magnitude. I can
understand if you want to reduce it further, but it might be good
enough for your purposes.
I considered doing the equivalent of O_NOMTIME for our purposes at
$WORK, and our use case is actually not that different from Ceph's
(i.e., using a local disk file system to support a cluster file
system), and lazytime was (a) something I figured was something I
could upstream in good conscience, and (b) was more than good enough
for us.
Cheers,
- Ted
P.S. I do agree that if we do need this upstream, requiring a mount
option to enable the feature is probably a good compromise.
next prev parent reply other threads:[~2015-05-11 23:10 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-06 22:00 [PATCH RFC] vfs: add a O_NOMTIME flag Zach Brown
2015-05-06 22:14 ` Trond Myklebust
2015-05-06 22:19 ` Sage Weil
2015-05-06 22:41 ` Zach Brown
2015-05-06 22:46 ` Sage Weil
2015-05-06 23:21 ` Theodore Ts'o
2015-05-07 0:26 ` Dave Chinner
2015-05-07 17:20 ` Zach Brown
2015-05-07 18:43 ` Zach Brown
2015-05-07 19:09 ` Richard Weinberger
2015-05-07 19:53 ` Andy Lutomirski
[not found] ` <554BC4D8.9010507@nod.at>
2015-05-07 20:06 ` Andy Lutomirski
2015-05-08 2:42 ` Dave Chinner
2015-07-14 11:44 ` Pavel Machek
2015-05-08 1:01 ` Sage Weil
2015-05-08 1:23 ` Trond Myklebust
2015-05-08 15:19 ` Sage Weil
2015-05-08 22:13 ` Dave Chinner
2015-05-08 22:24 ` Sage Weil
2015-05-10 23:13 ` Trond Myklebust
2015-05-11 7:31 ` Dave Chinner
2015-05-11 16:39 ` Sage Weil
2015-05-11 17:12 ` Trond Myklebust
2015-05-11 17:30 ` Sage Weil
2015-05-12 1:21 ` Dave Chinner
2015-05-12 23:12 ` Sage Weil
2015-05-13 0:57 ` Dave Chinner
2015-05-12 13:41 ` John Stoffel
2015-05-11 14:47 ` Theodore Ts'o
2015-05-11 16:24 ` Sage Weil
2015-05-11 23:10 ` Theodore Ts'o [this message]
2015-05-12 5:08 ` Kevin Easton
2015-05-12 11:45 ` Austin S Hemmelgarn
2015-05-12 13:54 ` John Stoffel
2015-05-12 14:36 ` J. Bruce Fields
2015-05-12 14:53 ` Austin S Hemmelgarn
2015-05-12 21:51 ` Dave Chinner
2015-05-13 15:16 ` Austin S Hemmelgarn
2015-05-12 22:39 ` NeilBrown
2015-07-14 13:13 ` Pavel Machek
2015-07-15 4:54 ` NeilBrown
2015-07-22 13:47 ` Pavel Machek
2015-05-12 21:35 ` Sage Weil
2015-05-13 12:32 ` Jan Kara
2015-05-08 14:29 ` John Stoffel
2015-07-14 11:50 ` Pavel Machek
2015-05-08 14:43 ` Austin S Hemmelgarn
2015-05-08 17:11 ` Zach Brown
2015-05-08 2:37 ` Dave Chinner
2015-05-08 3:24 ` Andy Lutomirski
2015-05-08 14:44 ` Eric Sandeen
2015-05-11 20:36 ` J. Bruce Fields
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