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From: Andrew Morton <akpm@linux-foundation.org>
To: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: LKML <linux-kernel@vger.kernel.org>,
	linux-nilfs <linux-nilfs@vger.kernel.org>,
	Andreas Rohner <andreas.rohner@gmx.net>
Subject: Re: [PATCH 4/4] nilfs2: implementation of NILFS_IOCTL_SET_SUINFO ioctl
Date: Mon, 3 Feb 2014 13:41:01 -0800	[thread overview]
Message-ID: <20140203134101.c56b916544e2475f63227339@linux-foundation.org> (raw)
In-Reply-To: <1391446244-1435-5-git-send-email-konishi.ryusuke@lab.ntt.co.jp>

On Tue,  4 Feb 2014 01:50:44 +0900 Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> wrote:

> With this ioctl the segment usage entries in the SUFILE can be
> updated from userspace.
> 
> This is useful, because it allows the userspace GC to modify and update
> segment usage entries for specific segments, which enables it to avoid
> unnecessary write operations.
> 
> If a segment needs to be cleaned, but there is no or very little
> reclaimable space in it, the cleaning operation basically degrades to
> a useless moving operation. In the end the only thing that changes is
> the location of the data and a timestamp in the segment usage
> information. With this ioctl the GC can skip the cleaning and update
> the segment usage entries directly instead.
> 
> This is basically a shortcut to cleaning the segment. It is still
> necessary to read the segment summary information, but the writing of
> the live blocks can be skipped if it's not worth it.

Documentation/filesystems/nilfs2.txt should be updated to document the
new ioctl.

Which we're in there, please check that the ioctl documentation is
otherwise complete and up-to-date.  These things have a tendency to
bitrot.


WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
To: Ryusuke Konishi
	<konishi.ryusuke-Zyj7fXuS5i5L9jVzuh4AOg@public.gmane.org>
Cc: LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	linux-nilfs <linux-nilfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	Andreas Rohner <andreas.rohner-hi6Y0CQ0nG0@public.gmane.org>
Subject: Re: [PATCH 4/4] nilfs2: implementation of NILFS_IOCTL_SET_SUINFO ioctl
Date: Mon, 3 Feb 2014 13:41:01 -0800	[thread overview]
Message-ID: <20140203134101.c56b916544e2475f63227339@linux-foundation.org> (raw)
In-Reply-To: <1391446244-1435-5-git-send-email-konishi.ryusuke-Zyj7fXuS5i5L9jVzuh4AOg@public.gmane.org>

On Tue,  4 Feb 2014 01:50:44 +0900 Ryusuke Konishi <konishi.ryusuke-Zyj7fXuS5i5L9jVzuh4AOg@public.gmane.org> wrote:

> With this ioctl the segment usage entries in the SUFILE can be
> updated from userspace.
> 
> This is useful, because it allows the userspace GC to modify and update
> segment usage entries for specific segments, which enables it to avoid
> unnecessary write operations.
> 
> If a segment needs to be cleaned, but there is no or very little
> reclaimable space in it, the cleaning operation basically degrades to
> a useless moving operation. In the end the only thing that changes is
> the location of the data and a timestamp in the segment usage
> information. With this ioctl the GC can skip the cleaning and update
> the segment usage entries directly instead.
> 
> This is basically a shortcut to cleaning the segment. It is still
> necessary to read the segment summary information, but the writing of
> the live blocks can be skipped if it's not worth it.

Documentation/filesystems/nilfs2.txt should be updated to document the
new ioctl.

Which we're in there, please check that the ioctl documentation is
otherwise complete and up-to-date.  These things have a tendency to
bitrot.

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  reply	other threads:[~2014-02-03 21:41 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-03 16:50 [PATCH 0/4] nilfs2 updates Ryusuke Konishi
2014-02-03 16:50 ` Ryusuke Konishi
2014-02-03 16:50 ` [PATCH 1/4] nilfs2: update MAINTAINERS file entries Ryusuke Konishi
2014-02-03 16:50 ` [PATCH 2/4] nilfs2: add struct nilfs_suinfo_update and flags Ryusuke Konishi
2014-02-03 16:50 ` [PATCH 3/4] nilfs2: add nilfs_sufile_set_suinfo to update segment usage Ryusuke Konishi
2014-02-03 16:50   ` Ryusuke Konishi
2014-02-03 21:38   ` Andrew Morton
2014-02-03 21:38     ` Andrew Morton
2014-02-04 16:41     ` Ryusuke Konishi
2014-02-04 16:41       ` Ryusuke Konishi
2014-02-04 17:23       ` Ryusuke Konishi
2014-02-04 17:23         ` Ryusuke Konishi
2014-02-03 16:50 ` [PATCH 4/4] nilfs2: implementation of NILFS_IOCTL_SET_SUINFO ioctl Ryusuke Konishi
2014-02-03 21:41   ` Andrew Morton [this message]
2014-02-03 21:41     ` Andrew Morton
2014-02-04  1:47     ` Ryusuke Konishi
2014-02-04  1:47       ` Ryusuke Konishi

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