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From: Jeremy Allison <jra@samba.org>
To: Olaf Weber <olaf@sgi.com>
Cc: tinguely@sgi.com, xfs@oss.sgi.com,
	Christoph Hellwig <hch@infradead.org>, Ben Myers <bpm@sgi.com>,
	linux-fsdevel@vger.kernel.org, Jeremy Allison <jra@samba.org>
Subject: Re: [RFC v2] Unicode/UTF-8 support for XFS
Date: Fri, 26 Sep 2014 12:46:56 -0700	[thread overview]
Message-ID: <20140926194656.GC13066@samba2> (raw)
In-Reply-To: <5425C067.7080904@sgi.com>

On Fri, Sep 26, 2014 at 09:37:11PM +0200, Olaf Weber wrote:
> 
> My argument against "mount time case-insensitivity" and for "mkfs
> time case-insensitivity" is related to switching from the
> case-sensitive domain to the case-insensitive one.
> 
> For case-sensitive, from "README" to "readme" there are 64 different
> possible filenames.  Let's say you create 63 out of these 64. Now
> remount the filesystem case-insensitive, and try to open by the 64th
> version of "readme". It is not an exact match for any of the 63
> candidate files, and a case-insensitive match to all 63 candidate
> files. Which of these 63 files should be opened, and why that one in
> particular?

I'm ok with "mkfs time case-insensitivity" - really !
Most of my OEMs would set that and claim victory (few
of them care much about NFS semantics :-).

> >Having CI matching can speed up Samba operations by a
> >factor of 10 on large directories (warning, number made
> >up, depending on the number of entries per dir :-).
> 
> I really want that to be true, but the proof of the pudding...

No it really *is* true. The reason I can't give
exact numbers is it depends on the number of entries.

Remember, for every cache *miss*, we have to scan
the entire directory.

So a user asks for README, and we attempt that
and it fails. So now we have to enumerate the
entire directory to see if READMe (or any other
case varient) exists.

Now do that in a directory with 10, 100, 1000,
.... 10000000 existing files (don't laugh, I've
seen an application for Music files that did
*exactly* that). On a case insensitive filesystem
you just request README and you're done.

Certain vendors who shall remain nameless :-)
created test cases of just this example to
show how much storage on Linux sucks. Not
a happy camper about that - and telling them
to use ZFS on FreeBSD or Solaris just doesn't
feel right :-).

Jeremy.

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  reply	other threads:[~2014-09-26 19:46 UTC|newest]

Thread overview: 65+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-18 19:56 [RFC v2] Unicode/UTF-8 support for XFS Ben Myers
2014-09-18 20:08 ` [PATCH 01/10] xfs: return the first match during case-insensitive lookup Ben Myers
2014-09-18 20:09 ` [PATCH 02/10] xfs: rename XFS_CMP_CASE to XFS_CMP_MATCH Ben Myers
2014-09-18 20:09 ` [PATCH 03/13] libxfs: add xfs_nameops.normhash Ben Myers
2014-09-18 20:10 ` [PATCH 04/10] xfs: change interface of xfs_nameops.normhash Ben Myers
2014-09-18 20:11 ` [PATCH 05/10] xfs: add a superblock feature bit to indicate UTF-8 support Ben Myers
2014-09-18 20:13 ` [PATCH 03/10] xfs: add xfs_nameops.normhash Ben Myers
2014-09-18 20:14 ` [PATCH 06/10] xfs: add unicode character database files Ben Myers
2014-09-22 20:54   ` Dave Chinner
2014-09-26 17:09     ` Christoph Hellwig
2014-09-18 20:15 ` [PATCH 07/10] xfs: add trie generator and supporting code for UTF-8 Ben Myers
2014-09-22 20:57   ` Dave Chinner
2014-09-23 18:57     ` Ben Myers
2014-09-26 17:10       ` Christoph Hellwig
2014-09-18 20:16 ` [PATCH 08/10] xfs: add xfs_nameops for utf8 and utf8+casefold Ben Myers
2014-09-18 20:17 ` [PATCH 09/10] xfs: apply utf-8 normalization rules to user extended attribute names Ben Myers
2014-09-18 20:18 ` [PATCH 10/10] xfs: implement demand load of utf8norm.ko Ben Myers
2014-09-18 20:31 ` [PATCH 00/13] xfsprogs: Unicode/UTF-8 support for XFS Ben Myers
2014-09-18 20:33   ` [PATCH 01/13] libxfs: return the first match during case-insensitive lookup Ben Myers
2014-09-18 20:33   ` [PATCH 02/13] libxfs: rename XFS_CMP_CASE to XFS_CMP_MATCH Ben Myers
2014-09-18 20:34   ` [PATCH 03/13] libxfs: add xfs_nameops.normhash Ben Myers
2014-09-18 20:35   ` [PATCH 04/13] libxfs: change interface of xfs_nameops.normhash Ben Myers
2014-09-18 20:36   ` [PATCH 05/13] libxfs: add a superblock feature bit to indicate UTF-8 support Ben Myers
2014-09-18 20:37   ` [PATCH 06/13] xfsprogs: add unicode character database files Ben Myers
2014-09-18 20:38   ` [PATCH 07/13] libxfs: add trie generator and supporting code for UTF-8 Ben Myers
2014-09-18 20:38   ` [PATCH 08/13] libxfs: add xfs_nameops for utf8 and utf8+casefold Ben Myers
2014-09-18 20:39   ` [PATCH 09/13] libxfs: apply utf-8 normalization rules to user extended attribute names Ben Myers
2014-09-18 20:40   ` [PATCH 10/13] xfsprogs: add utf8 support to growfs Ben Myers
2014-09-18 20:41   ` [PATCH 11/13] xfsprogs: add utf8 support to mkfs.xfs Ben Myers
2014-09-18 20:42   ` [PATCH 12/13] xfsprogs: add utf8 support to xfs_repair Ben Myers
2014-09-18 20:43   ` [PATCH 13/13] xfsprogs: add a preliminary test for utf8 support Ben Myers
2014-09-19 16:06   ` [PATCH 07a/13] xfsprogs: add trie generator for UTF-8 Ben Myers
2014-09-23 18:34     ` Roger Willcocks
2014-09-24 23:11       ` Ben Myers
2014-09-19 16:07   ` [PATCH 07b/13] libxfs: add supporting code " Ben Myers
2014-09-18 21:10 ` [RFC v2] Unicode/UTF-8 support for XFS Ben Myers
2014-09-18 21:24   ` Zach Brown
2014-09-18 22:23     ` Ben Myers
2014-09-19 16:03 ` [PATCH 07a/10] xfs: add trie generator for UTF-8 Ben Myers
2014-09-19 16:04 ` [PATCH 07b/10] xfs: add supporting code " Ben Myers
2014-09-22 14:55 ` [RFC v2] Unicode/UTF-8 support for XFS Andi Kleen
2014-09-22 18:41   ` Ben Myers
2014-09-22 19:29     ` Andi Kleen
2014-09-23 16:13       ` Olaf Weber
2014-09-23 20:15         ` Andi Kleen
2014-09-23 20:45           ` Ben Myers
2014-09-24 11:07           ` Olaf Weber
2014-09-26 14:06             ` Olaf Weber
2014-09-23 13:01   ` Olaf Weber
2014-09-23 20:02     ` Andi Kleen
2014-09-22 22:26 ` Dave Chinner
2014-09-24 13:21   ` Olaf Weber
2014-09-24 23:10     ` Dave Chinner
2014-09-25 13:33       ` Zuckerman, Boris
2014-09-26 14:50       ` Olaf Weber
2014-09-26 16:56         ` Christoph Hellwig
2014-09-26 17:04           ` Jeremy Allison
2014-09-26 17:06             ` Christoph Hellwig
2014-09-26 17:13               ` Jeremy Allison
2014-09-26 19:37             ` Olaf Weber
2014-09-26 19:46               ` Jeremy Allison [this message]
2014-09-26 20:03                 ` Olaf Weber
2014-09-29 20:16                   ` J. Bruce Fields
2014-09-29 11:06               ` Christoph Hellwig
2014-09-26 17:30           ` Ben Myers

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