From: Olaf Weber <olaf@sgi.com>
To: Jeremy Allison <jra@samba.org>
Cc: tinguely@sgi.com, xfs@oss.sgi.com,
Christoph Hellwig <hch@infradead.org>, Ben Myers <bpm@sgi.com>,
linux-fsdevel@vger.kernel.org
Subject: Re: [RFC v2] Unicode/UTF-8 support for XFS
Date: Fri, 26 Sep 2014 22:03:50 +0200 [thread overview]
Message-ID: <5425C6A6.3060003@sgi.com> (raw)
In-Reply-To: <20140926194656.GC13066@samba2>
On 26-09-14 21:46, Jeremy Allison wrote:
> 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 :-).
I'd say you can have CIFS-style case-insensitive semantics or NFS-style
case-sensitive semantics, but not both. And in particular, that a customer
should not actually want to have both.
>>> 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 :-).
Here's the thing to bear in mind: what I did is a straightforward extension
of the existing XFS ASCII-based case-insensitive code. If that gets you the
desired performance improvement, then my code should extend that to more
general usage. If it doesn't, then there are places in XFS that I haven't
touched that need modification to have these cases work well.
Olaf
--
Olaf Weber SGI Phone: +31(0)30-6696796
Veldzigt 2b Fax: +31(0)30-6696799
Technical Lead 3454 PW de Meern Vnet: 955-6796
Storage Software The Netherlands Email: olaf@sgi.com
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next prev parent reply other threads:[~2014-09-26 20:03 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
2014-09-26 20:03 ` Olaf Weber [this message]
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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