From: "Jörn Engel" <joern@logfs.org>
To: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, kihara.seiji@lab.ntt.co.jp,
amagai.yoshiji@lab.ntt.co.jp
Subject: Re: [PATCH 25/27] nilfs2: block cache for garbage collection
Date: Sat, 20 Sep 2008 13:04:59 +0200 [thread overview]
Message-ID: <20080920110459.GB9418@logfs.org> (raw)
In-Reply-To: <20080920.194358.07565122.ryusuke@osrg.net>
On Sat, 20 September 2008 19:43:58 +0900, Ryusuke Konishi wrote:
>
> > But that would be inefficient in several cases. When
> > GC'ing data that is dirty in the caches, you move the old stale data
> > during GC and write the new data soon after. And you always flush the
> > caches after GC, even if your machine has no better use for the memory.
>
> As for as NILFS2, the dirty blocks and the blocks to be moved by GC
> never overlap because the dirty blocks make a new generation.
> So, they rather must be written individually.
>
> Though we can reuse pages in the GC cache, the effect of this
> optimization may be much lower than usual LFSes because most of
> blocks in the pages may not belong to the latest generation.
Yet again I've tried to apply techniques that simply don't work with
checkpoints in the equation.
> NILFS2 needs explication than usual file systems; it needs time
> perspective as well as it is an LFS. :)
At least if you take me as a standard, I think you have proven that
point rather well. :)
Jörn
--
Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it.
-- Brian W. Kernighan
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next prev parent reply other threads:[~2008-09-20 11:05 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-14 19:07 [PATCH 0/27] nilfs2: continuous snapshotting file system Ryusuke Konishi
2008-09-14 19:07 ` [PATCH 01/27] nilfs2: add document Ryusuke Konishi
2008-09-14 19:07 ` [PATCH 02/27] nilfs2: disk format and userland interface Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 03/27] nilfs2: add inode and other major structures Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 04/27] nilfs2: integrated block mapping Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 05/27] nilfs2: B-tree based " Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 06/27] nilfs2: direct " Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 07/27] nilfs2: B-tree node cache Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 08/27] nilfs2: buffer and page operations Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 09/27] nilfs2: meta data file Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 10/27] nilfs2: persistent object allocator Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 11/27] nilfs2: disk address translator Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 12/27] nilfs2: inode map file Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 13/27] nilfs2: checkpoint file Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 14/27] nilfs2: segment usage file Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 15/27] nilfs2: inode operations Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 16/27] nilfs2: file operations Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 17/27] nilfs2: directory entry operations Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 18/27] nilfs2: pathname operations Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 19/27] nilfs2: operations for the_nilfs core object Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 20/27] nilfs2: super block operations Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 21/27] nilfs2: segment buffer Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 22/27] nilfs2: segment constructor Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 23/27] nilfs2: recovery functions Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 24/27] nilfs2: another dat for garbage collection Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 25/27] nilfs2: block cache " Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 26/27] nilfs2: ioctl operations Ryusuke Konishi
2008-09-14 19:08 ` [PATCH 27/27] nilfs2: update makefile and Kconfig Ryusuke Konishi
2008-09-17 14:41 ` [PATCH 25/27] nilfs2: block cache for garbage collection Jörn Engel
2008-09-17 19:09 ` Ryusuke Konishi
2008-09-17 22:49 ` Jörn Engel
2008-09-20 10:43 ` Ryusuke Konishi
2008-09-20 11:04 ` Jörn Engel [this message]
2008-09-15 18:20 ` [PATCH 18/27] nilfs2: pathname operations Pekka Enberg
2008-09-16 5:31 ` konishi.ryusuke
2008-09-17 14:31 ` [PATCH 02/27] nilfs2: disk format and userland interface Jörn Engel
2008-09-17 15:51 ` Ryusuke Konishi
2008-09-15 9:54 ` [PATCH 01/27] nilfs2: add document Pavel Machek
2008-09-15 20:10 ` konishi.ryusuke
2008-09-16 13:38 ` Chris Mason
2008-09-17 14:54 ` Jörn Engel
2008-09-17 17:52 ` Ryusuke Konishi
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