From: Dave Chinner <david@fromorbit.com>
To: zwu.kernel@gmail.com
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org,
linuxram@linux.vnet.ibm.com, viro@zeniv.linux.org.uk,
cmm@us.ibm.com, tytso@mit.edu, marco.stornelli@gmail.com,
stroetmann@ontolinux.com, diegocg@gmail.com, chris@csamuel.org,
Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
Subject: Re: [RFC v2 07/10] vfs: fork one kthread to update data temperature
Date: Thu, 27 Sep 2012 14:03:57 +1000 [thread overview]
Message-ID: <20120927040357.GO15236@dastard> (raw)
In-Reply-To: <1348404995-14372-8-git-send-email-zwu.kernel@gmail.com>
On Sun, Sep 23, 2012 at 08:56:32PM +0800, zwu.kernel@gmail.com wrote:
> From: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
>
> Fork and run one kernel kthread to calculate
> that temperature based on some metrics kept
> in custom frequency data structs, and store
> the info in the hash table.
No new kthreads, please. Use a per-superblock workqueue and a struct
delayed_work to run periodic work on each superblock.
That will also remove all the nasty, nasty
!hot_track_temperature_update_kthread checks from the code, too.
Also, I'd separate the work that the workqueue does from the patch
that introduces the work queue. That way there is only one new thing
to comment on in the patch. Further, I'd separate the aging code
from the code that updates the temperature map into it's own patch
as well..
Finally, you're going to need a shrinker to control the amount of
memory that is used in tracking hot regions - if we are throwing
inodes out of memory due to memory pressure, we most definitely are
going to need to reduce the amount of memory the tracking code is
using, even if it means losing useful information (i.e. the shrinker
accelerates the aging process).
Given the above, and the other comments earlier in the series,
there's not a lot of point in me spending time commenting on ethe
code in detail here as it will change significantly as a result of
all the earlier comments....
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2012-09-27 4:03 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-23 12:56 [RFC v2 00/10] vfs: hot data tracking zwu.kernel
2012-09-23 12:56 ` [RFC v2 01/10] vfs: introduce private rb structures zwu.kernel
2012-09-25 7:37 ` Dave Chinner
2012-09-25 7:57 ` Zhi Yong Wu
2012-09-25 8:00 ` Zhi Yong Wu
2012-09-25 10:20 ` Ram Pai
2012-09-26 3:20 ` Zhi Yong Wu
2012-09-23 12:56 ` [RFC v2 02/10] vfs: add support for updating access frequency zwu.kernel
2012-09-25 9:17 ` Dave Chinner
2012-09-26 2:53 ` Zhi Yong Wu
2012-09-27 2:19 ` Dave Chinner
2012-09-27 2:30 ` Zhi Yong Wu
2012-09-23 12:56 ` [RFC v2 03/10] vfs: add one new mount option '-o hottrack' zwu.kernel
2012-09-25 9:28 ` Dave Chinner
2012-09-26 2:56 ` Zhi Yong Wu
2012-09-27 2:20 ` Dave Chinner
2012-09-27 2:30 ` Zhi Yong Wu
2012-09-27 5:25 ` Zhi Yong Wu
2012-09-27 7:05 ` Dave Chinner
2012-09-27 7:21 ` Zhi Yong Wu
2012-09-23 12:56 ` [RFC v2 04/10] vfs: add init and exit support zwu.kernel
2012-09-27 2:27 ` Dave Chinner
2012-09-23 12:56 ` [RFC v2 05/10] vfs: introduce one hash table zwu.kernel
2012-09-25 9:54 ` Ram Pai
2012-09-26 4:08 ` Zhi Yong Wu
2012-09-27 3:43 ` Dave Chinner
2012-09-27 6:23 ` Zhi Yong Wu
2012-09-27 6:57 ` Dave Chinner
2012-09-27 7:10 ` Zhi Yong Wu
2012-09-23 12:56 ` [RFC v2 06/10] vfs: enable hot data tracking zwu.kernel
2012-09-27 3:54 ` Dave Chinner
2012-09-27 6:28 ` Zhi Yong Wu
2012-09-27 6:59 ` Dave Chinner
2012-09-27 7:12 ` Zhi Yong Wu
2012-09-23 12:56 ` [RFC v2 07/10] vfs: fork one kthread to update data temperature zwu.kernel
2012-09-27 4:03 ` Dave Chinner [this message]
2012-09-27 6:54 ` Zhi Yong Wu
2012-09-27 7:01 ` Dave Chinner
2012-09-27 7:19 ` Zhi Yong Wu
2012-09-23 12:56 ` [RFC v2 08/10] vfs: add 3 new ioctl interfaces zwu.kernel
2012-09-23 12:56 ` [RFC v2 09/10] vfs: add debugfs support zwu.kernel
2012-09-23 12:56 ` [RFC v2 10/10] vfs: add documentation zwu.kernel
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