From: Zach Brown <zab@zabbo.net>
To: Ted Ts'o <tytso@mit.edu>, Yongqiang Yang <xiaoqiangnk@gmail.com>,
Phillip Susi <phillsusi@gmail.com>,
Andreas Dilger <adilger@whamcloud.com>,
Lukas Czerner <lczerner@redhat.com>,
Jacek Luczak <difrost.kernel@gmail.com>,
"linux-ext4@vger.kernel.org" <linux-ext4@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
"linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>
Subject: Re: getdents - ext4 vs btrfs performance
Date: Wed, 14 Mar 2012 13:37:07 -0400 [thread overview]
Message-ID: <4F60D743.50209@zabbo.net> (raw)
In-Reply-To: <20120314164804.GA28042@thunk.org>
On 03/14/2012 12:48 PM, Ted Ts'o wrote:
> On Wed, Mar 14, 2012 at 10:17:37AM -0400, Zach Brown wrote:
>>
>>> We could do this if we have two b-trees, one indexed by filename and
>>> one indexed by inode number, which is what JFS (and I believe btrfs)
>>> does.
>>
>> Typically the inode number of the destination inode isn't used to index
>> entries for a readdir tree because of (wait for it) hard links. You end
>> up right back where you started with multiple entries per key.
>
> One thing that might work is to have a 16-bit extra field in the
> directory entry that gives an signed offset to the inode number so
> that such that inode+offset is a unique value within the btree sorted
> by inode+offset number. Since this tree is only used for returning
> entries in an optimal (or as close to optimal as can be arranged)
> order, we could get away with that.
Yeah, at least that's nice and simple. Personally, I'm always nervous
when we build in new limits like this. Some joker somewhere always
manages to push up against them.
But such is life. Maybe it's the right thing in the ext* design space.
The fixed number of possible inodes certainly makes it easier to pack
more inode offsets into the telldir cookie.
- z
next prev parent reply other threads:[~2012-03-14 17:37 UTC|newest]
Thread overview: 90+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-29 13:52 getdents - ext4 vs btrfs performance Jacek Luczak
2012-02-29 13:55 ` Jacek Luczak
2012-02-29 13:55 ` Jacek Luczak
2012-02-29 14:07 ` Jacek Luczak
2012-02-29 14:07 ` Jacek Luczak
2012-02-29 14:07 ` Jacek Luczak
2012-02-29 14:21 ` Jacek Luczak
2012-02-29 14:21 ` Jacek Luczak
2012-02-29 14:21 ` Jacek Luczak
2012-02-29 14:42 ` Chris Mason
2012-02-29 14:55 ` Jacek Luczak
2012-03-01 13:35 ` Jacek Luczak
2012-03-01 13:50 ` Hillf Danton
2012-03-01 14:03 ` Jacek Luczak
2012-03-01 14:18 ` Chris Mason
2012-03-01 14:43 ` Jacek Luczak
2012-03-01 14:43 ` Jacek Luczak
2012-03-01 14:51 ` Chris Mason
2012-03-01 14:51 ` Chris Mason
2012-03-01 14:51 ` Chris Mason
2012-03-01 14:57 ` Jacek Luczak
2012-03-01 14:57 ` Jacek Luczak
2012-03-01 14:57 ` Jacek Luczak
2012-03-01 18:42 ` Ted Ts'o
2012-03-02 9:51 ` Jacek Luczak
2012-03-01 4:44 ` Theodore Tso
2012-03-01 4:44 ` Theodore Tso
2012-03-01 4:44 ` Theodore Tso
2012-03-01 14:38 ` Chris Mason
2012-03-01 14:38 ` Chris Mason
2012-03-02 10:05 ` Jacek Luczak
2012-03-02 10:05 ` Jacek Luczak
2012-03-02 10:05 ` Jacek Luczak
2012-03-02 14:00 ` Chris Mason
2012-03-02 14:16 ` Jacek Luczak
2012-03-02 14:16 ` Jacek Luczak
2012-03-02 14:16 ` Jacek Luczak
2012-03-02 14:26 ` Chris Mason
2012-03-02 14:26 ` Chris Mason
2012-03-02 19:32 ` Ted Ts'o
2012-03-02 19:50 ` Chris Mason
2012-03-05 13:10 ` Jan Kara
2012-03-03 22:41 ` Jacek Luczak
2012-03-03 22:41 ` Jacek Luczak
2012-03-04 10:25 ` Jacek Luczak
2012-03-04 10:25 ` Jacek Luczak
2012-03-05 11:32 ` Jacek Luczak
2012-03-05 11:32 ` Jacek Luczak
2012-03-05 11:32 ` Jacek Luczak
2012-03-06 0:37 ` Chris Mason
2012-03-06 0:37 ` Chris Mason
2012-03-08 17:02 ` Phillip Susi
2012-03-09 11:29 ` Lukas Czerner
2012-03-09 14:34 ` Chris Mason
2012-03-10 0:09 ` Andreas Dilger
2012-03-10 4:48 ` Ted Ts'o
2012-03-11 10:30 ` Andreas Dilger
2012-03-11 16:13 ` Ted Ts'o
2012-03-15 10:42 ` Jacek Luczak
2012-03-15 10:42 ` Jacek Luczak
2012-03-15 10:42 ` Jacek Luczak
2012-03-18 20:56 ` Ted Ts'o
2012-03-13 19:05 ` Phillip Susi
2012-03-13 19:53 ` Ted Ts'o
2012-03-13 20:22 ` Phillip Susi
2012-03-13 21:33 ` Ted Ts'o
2012-03-14 2:48 ` Yongqiang Yang
2012-03-14 2:51 ` Ted Ts'o
2012-03-14 14:17 ` Zach Brown
2012-03-14 16:48 ` Ted Ts'o
2012-03-14 17:37 ` Zach Brown [this message]
2012-03-14 8:12 ` Lukas Czerner
2012-03-14 9:29 ` Yongqiang Yang
2012-03-14 9:29 ` Yongqiang Yang
2012-03-14 9:29 ` Yongqiang Yang
2012-03-14 9:38 ` Lukas Czerner
2012-03-14 12:50 ` Ted Ts'o
2012-03-14 14:34 ` Lukas Czerner
2012-03-14 17:02 ` Ted Ts'o
2012-03-14 19:17 ` Chris Mason
2012-03-14 14:28 ` Phillip Susi
2012-03-14 16:54 ` Ted Ts'o
2012-03-10 3:52 ` Ted Ts'o
2012-03-15 7:59 ` Jacek Luczak
2012-03-15 7:59 ` Jacek Luczak
2012-03-15 7:59 ` Jacek Luczak
-- strict thread matches above, loose matches on Subject: below --
2012-02-29 13:31 Jacek Luczak
2012-02-29 13:51 ` Chris Mason
2012-02-29 14:00 ` Lukas Czerner
2012-02-29 14:05 ` Chris Mason
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