From: Theodore Ts'o <tytso@mit.edu>
To: Jeremy Allison <jra@google.com>
Cc: Ext4 Developers List <linux-ext4@vger.kernel.org>,
Daniel Rosenberg <drosen@google.com>,
guy@linux.com
Subject: Re: [RFC] A proposal for adding case insensitive lookups to ext4
Date: Fri, 4 Nov 2016 20:00:52 -0400 [thread overview]
Message-ID: <20161105000052.54dmfdp5sgiqq6wo@thunk.org> (raw)
In-Reply-To: <CAEuANoLdZ0STmhp+1voS9K6+Ndkb6zfSWEcc0_thUtDjS8NPwg@mail.gmail.com>
On Fri, Nov 04, 2016 at 04:28:05PM -0700, Jeremy Allison wrote:
> I don't suppose ext4 has a negative cache for lookups ? That would
> certainly help the linear search case on lookup miss.
The dcache caches negative results, so as long as the lookup miss is
for the same non-existing file name, that's not a problem.
The issue will be if someone is using Makefile with default rules,
say, and Makefile is checking for foo.y, foo.l, foo.C, etc. for each
object file, there could be a fairly large number of failed lookups
that might require O(n) lookups. Eventually all of these will be
cached, yes, but it could be a large number of negative dentry caches.
However, I'm not sure I care; no self-respecting programmer should be
using a case-insensitive file system, so in practice, I'm not sure it
matters all that much....
- Ted
prev parent reply other threads:[~2016-11-05 0:00 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-03 17:28 [RFC] A proposal for adding case insensitive lookups to ext4 Theodore Ts'o
2016-11-04 16:14 ` Andreas Dilger
2016-11-04 21:51 ` Theodore Ts'o
2016-11-04 23:12 ` Andreas Dilger
2016-11-06 23:57 ` Dave Chinner
2016-11-07 0:14 ` Theodore Ts'o
2016-11-07 4:30 ` Dave Chinner
2016-11-07 5:42 ` Theodore Ts'o
[not found] ` <CAEuANoLdZ0STmhp+1voS9K6+Ndkb6zfSWEcc0_thUtDjS8NPwg@mail.gmail.com>
2016-11-05 0:00 ` Theodore Ts'o [this message]
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