From: "Jörn Engel" <joern@logfs.org>
To: zwu.kernel@gmail.com
Cc: viro@zeniv.linux.org.uk, torvalds@linux-foundation.org,
linux-fsdevel@vger.kernel.org,
Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
Subject: Re: [[RESEND]PATCH v4 00/10] VFS hot tracking
Date: Tue, 13 Aug 2013 14:32:03 -0400 [thread overview]
Message-ID: <20130813183202.GA5375@logfs.org> (raw)
In-Reply-To: <1376274024-28689-1-git-send-email-zwu.kernel@gmail.com>
On Mon, 12 August 2013 10:20:14 +0800, zwu.kernel@gmail.com wrote:
>
> The patchset is trying to introduce hot tracking function in
> VFS layer, which will keep track of real disk I/O in memory.
> By it, you will easily know more details about disk I/O, and
> then detect where disk I/O hot spots are. Also, specific FS
> can take use of it to do accurate defragment, and hot relocation
> support, etc.
I find this description extremely uninteresting. Sure, you can track
hot now. Grammatically, I am missing a noun. Are you tracking hot
pages, hot files or hot potatoes?
More importantly, once you have identified the hot stuff, why should I
care? What problem does it solve? The documentation patch at the end
has a "motivation" paragraph, but the introduction email does not. As
a result, every time you sent these patches, I quickly glanced at
them, decided not to care and moved on.
And finally, now that I have hunted down the motivation and know it is
about caching stuff on ssd, I question your basic approach. Why do
you want to touch the vfs at all and not do it as a block device
driver? The big advantage of a block driver is that noone cares.
People without ssd shouldn't care, as caching doesn't help them.
People without spinning rust shouldn't care as caching doesn't help
them either. And people with a mixture of both shouldn't care in a
few years time, once they have fully transitioned to ssd.
If you solve the problem in the vfs, I am forced to care. I cannot
just select CONFIG_CACHING_BLOCK_DEVICE=n and be done with it. If you
want me to carry such a cost for you, you better demonstrate some
enticing advantages for me as well. There is no CONFIG_VFS=n, after
all.
Jörn
--
Audacity augments courage; hesitation, fear.
-- Publilius Syrus
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2013-08-13 20:05 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-12 2:20 [[RESEND]PATCH v4 00/10] VFS hot tracking zwu.kernel
2013-08-12 2:20 ` [[RESEND]PATCH v4 01/10] VFS hot tracking: Define basic data structures and functions zwu.kernel
2013-08-12 2:20 ` [[RESEND]PATCH v4 02/10] VFS hot tracking: Track IO and record heat information zwu.kernel
2013-08-12 2:20 ` [[RESEND]PATCH v4 03/10] VFS hot tracking: Add a workqueue to move items between hot maps zwu.kernel
2013-08-12 2:20 ` [[RESEND]PATCH v4 04/10] VFS hot tracking: Add shrinker functionality to curtail memory usage zwu.kernel
2013-08-12 2:20 ` [[RESEND]PATCH v4 05/10] VFS hot tracking: Add an ioctl to get hot tracking information zwu.kernel
2013-08-12 2:20 ` [[RESEND]PATCH v4 06/10] VFS hot tracking: Add a /proc interface to make the interval tunable zwu.kernel
2013-08-12 2:20 ` [[RESEND]PATCH v4 07/10] VFS hot tracking: Add a /proc interfaces to control memory usage zwu.kernel
2013-08-12 2:20 ` [[RESEND]PATCH v4 08/10] VFS hot tracking: Add documentation zwu.kernel
2013-08-12 2:20 ` [[RESEND]PATCH v4 09/10] VFS hot tracking, btrfs: Add hot tracking support zwu.kernel
2013-08-12 2:20 ` [[RESEND]PATCH v4 10/10] VFS hot tracking, xfs: " zwu.kernel
2013-08-12 2:27 ` [[RESEND]PATCH v4 00/10] VFS hot tracking Zhi Yong Wu
2013-08-13 18:32 ` Jörn Engel [this message]
2013-08-13 21:22 ` Al Viro
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20130813183202.GA5375@logfs.org \
--to=joern@logfs.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=torvalds@linux-foundation.org \
--cc=viro@zeniv.linux.org.uk \
--cc=wuzhy@linux.vnet.ibm.com \
--cc=zwu.kernel@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).