archive mirror
 help / color / mirror / Atom feed
From: Ian Kumlien <>
To: "Ihar \"Philips\" Filipau" <>
Cc: Linux Kernel Mailing List <>
Subject: Re: [SHED][IO-SHED] Are we missing the big picture?
Date: 01 Aug 2003 14:23:42 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

[-- Attachment #1: Type: text/plain, Size: 2809 bytes --]

On Fri, 2003-08-01 at 11:00, Ihar "Philips" Filipau wrote:
>    Am I right - judging from your posting - that we finally reached 
> moment than Linux will have network-like queueing disciplines for disks 
> and CPUs?

CPU's? well, we do have a nice sheduler but i wouldn't say network-like

>    In any way, CPU/disk throughput just another types of limited resource.
>    It would be nice to be able to manage it - who gets more, who gets 
> less. CPU/disk schedulers by manageability are far behind network.
>    IMHO must have for servers.

Yes, but, thats not what I'm saying.

CFQ as it apparently was called, builds a queue list when the disk is
under load. So you get really fast data access if there is no load, and
a common queue when there is load. The common queue is the bad thing
about CFQ, imagine putting AS there instead... This would mean fast data
access on unloaded systems, better throughput on loaded systems and
prioritization features could hook right in since AS would only be used
during load. IE, you can add all kinds of patches that only matters
during heavy load.

(note: load is only diskload)

> Ian Kumlien wrote:
> > Hi all,
> > 
> > I have been following the sheduler and interactivity discussions closely
> > but via the archive, So i might be behind etc...
> > =P
> > 
> > [Note: sorry if i sound like mr.know-it-all etc, just trying to get a
> > point across]
> > 
> > Anyways, i think that the AS discussions that i have seen has missed
> > some points. Getting the processes priority in AS is one thing, but fist
> > of all i think there should be a stand off layer. Let me explain:
> > 
> > I liked Jens Axobe's 'CBQ' alike implementation (based on the idea of
> > Andrea A. (afair i have the names right) since it does the most
> > important thing... which is *nothing* when there is no load (ie, pass
> > trough).
> > 
> > AS might be/is the best damn io sheduler for loaded machines but when
> > there is no load, it's overhead. So in my opinion there should be
> > something that first warrants the usage of AS before it's actually
> > engaged.
> > 
> > And, if it's only engaged during high load, additions like basing the
> > requests priority on the process/tasks priority would make total sense,
> > adding the 'wakeup on wait' or what it was would also make total
> > sense... But how many of your machines uses the disk 100% of the time?
> > (in the real world... )
> > 
> > I don't know how 'CBQ' was implemented but any 'we are under load now'
> > trigger would do it for me.
> > 
> > Please see to it that my CC is included in any discussions =)
> > 
> > PS. Or was it a version of SFQ? in that case s/CBQ/SFQ/g
> > DS.
> > 
Ian Kumlien <>

[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 189 bytes --]

  reply	other threads:[~2003-08-01 12:25 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <>
2003-08-01  9:00 ` [SHED][IO-SHED] Are we missing the big picture? Ihar "Philips" Filipau
2003-08-01 12:23   ` Ian Kumlien [this message]
2003-08-01 12:32     ` Jens Axboe
2003-08-01 13:01       ` Ian Kumlien
2003-08-01  0:32 Ian Kumlien
2003-08-01  6:27 ` Nick Piggin
2003-08-01 12:18   ` Ian Kumlien
2003-08-02  1:49     ` Nick Piggin
2003-08-02  2:07       ` Ian Kumlien

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:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \

* 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).