From: Andrew Morton <akpm@osdl.org>
To: Neil Brown <neilb@suse.de>
Cc: torvalds@osdl.org, linux-raid@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 004 of 11] md: Increase the delay before marking metadata clean, and make it configurable.
Date: Sun, 30 Apr 2006 23:13:03 -0700 [thread overview]
Message-ID: <20060430231303.6b2bce82.akpm@osdl.org> (raw)
In-Reply-To: <17493.42109.153523.381980@cse.unsw.edu.au>
Neil Brown <neilb@suse.de> wrote:
>
> On Sunday April 30, akpm@osdl.org wrote:
> > NeilBrown <neilb@suse.de> wrote:
> > >
> > >
> > > When a md array has been idle (no writes) for 20msecs it is marked as
> > > 'clean'. This delay turns out to be too short for some real
> > > workloads. So increase it to 200msec (the time to update the metadata
> > > should be a tiny fraction of that) and make it sysfs-configurable.
> > >
> > >
> > > ...
> > >
> > > + safe_mode_delay
> > > + When an md array has seen no write requests for a certain period
> > > + of time, it will be marked as 'clean'. When another write
> > > + request arrive, the array is marked as 'dirty' before the write
> > > + commenses. This is known as 'safe_mode'.
> > > + The 'certain period' is controlled by this file which stores the
> > > + period as a number of seconds. The default is 200msec (0.200).
> > > + Writing a value of 0 disables safemode.
> > > +
> >
> > Why not make the units milliseconds? Rename this to safe_mode_delay_msecs
> > to remove any doubt.
>
> Because umpteen years ago when I was adding thread-usage statistics to
> /proc/net/rpc/nfsd I used milliseconds and Linus asked me to make it
> seconds - a much more "obvious" unit. See Email below.
> It seems very sensible to me.
That's output. It's easier to do the conversion with output. And I guess
one could argue that lots of people read /proc files, but few write to
them.
Generally I don't think we should be teaching the kernel to accept
pretend-floating-point numbers like this, especially when a) "delay in
milliseconds" is such a simple concept and b) it's so easy to go from float
to milliseconds in userspace.
Do you really expect that humans (really dumb ones ;)) will be echoing
numbers into this file? Or will it mainly be a thing for mdadm to fiddle
with?
next prev parent reply other threads:[~2006-05-01 6:13 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-01 5:29 [PATCH 000 of 11] md: Introduction - assort md enhancements for 2.6.18 NeilBrown
2006-05-01 5:30 ` [PATCH 001 of 11] md: Reformat code in raid1_end_write_request to avoid goto NeilBrown
2006-05-01 5:30 ` [PATCH 002 of 11] md: Remove arbitrary limit on chunk size NeilBrown
2006-05-01 5:30 ` [PATCH 003 of 11] md: Remove useless ioctl warning NeilBrown
2006-05-01 5:30 ` [PATCH 004 of 11] md: Increase the delay before marking metadata clean, and make it configurable NeilBrown
2006-05-01 5:44 ` Andrew Morton
2006-05-01 6:02 ` Neil Brown
2006-05-01 6:13 ` Andrew Morton [this message]
2006-05-01 15:17 ` Linus Torvalds
2006-05-01 6:15 ` Nick Piggin
2006-05-02 5:56 ` bert hubert
2006-05-09 1:40 ` Neil Brown
2006-05-01 5:30 ` [PATCH 006 of 11] md: Remove nuisance message at shutdown NeilBrown
2006-05-01 5:30 ` [PATCH 007 of 11] md: Allow checkpoint of recovery with version-1 superblock NeilBrown
2006-05-01 5:30 ` [PATCH 008 of 11] md: Allow a linear array to have drives added while active NeilBrown
2006-05-01 5:30 ` [PATCH 009 of 11] md: Support stripe/offset mode in raid10 NeilBrown
2006-05-02 16:38 ` Al Boldi
2006-05-03 0:05 ` Neil Brown
2006-05-03 4:00 ` Al Boldi
2006-05-08 7:17 ` Neil Brown
2006-05-08 16:59 ` Al Boldi
2006-05-17 21:32 ` Raid5 resize "testing opportunity" Patrik Jonsson
2006-05-17 23:49 ` Neil Brown
2006-05-19 0:40 ` Patrik Jonsson
2006-05-19 0:44 ` Neil Brown
2006-05-19 20:11 ` Per Lindstrand
2006-05-01 5:31 ` [PATCH 010 of 11] md: make md_print_devices() static NeilBrown
2006-05-01 5:31 ` [PATCH 011 of 11] md: Split reshape portion of raid5 sync_request into a separate function NeilBrown
[not found] ` <1060501053025.22961@suse.de>
2006-05-01 5:40 ` [PATCH 005 of 11] md: Merge raid5 and raid6 code H. Peter Anvin
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=20060430231303.6b2bce82.akpm@osdl.org \
--to=akpm@osdl.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-raid@vger.kernel.org \
--cc=neilb@suse.de \
--cc=torvalds@osdl.org \
/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).