Feature proposal (scheduling related)

From: jimis@gmx.net
Date: Wed Jul 23 2003 - 05:57:41 EST

With the current scheduler we can prioritize the CPU usage for each process.
What I think would be extremely useful (as I have needed it many times) is the
scheduling of disk I/O and net I/O traffic. 2 examples showing the importance
(the numbers are estimations just to explain whati I mean):

1)I 'm connected to the internet via dial-up, therefore I only have 40 kbits of
bandwidth available. What I want to do is listen to icecast radio via xmms (at
22 kbits), download the kernel sources with wget, and browse the web at the same
time. Currently I think that this is *impossible* (correct me if I'm wrong) as
the radio will be full of pauses and the browsing experience painfully slow.
What I would like to be able to do (let's suppose nice has the --net option to
set net I/O priority):
$ nice --net -1 xmms
$ nice --net 1 wget ftp://.../KernelSources.tar.bz2
$ mozilla
This way, xmms which has top priority whould always get the 22kbits it needs.
What remains should go to the browser when I ask for a web page, and when the
browser doesn't request anything (let's say I'm reading a big doc in tldp) what
remains should go to wget. Wget has lower priority and won't irritate the
browsing experience, though the file will be downloaded when there is free

2) Normally mozilla starts in 5 seconds after intense disk I/O to load all
needed libraries. If I run in the background a long disk intense process
(like find / -name 'whatever' -xdev) loading mozilla could need 20 boring
seconds, or doing other simple tasks might be irritating slow. What I would like
to be able to do is (once again let's suppose nice has the --disk option to set
disk I/O priority):
$ nice --disk 1 find / -name 'whatever' -xdev
$ mozilla
and load mozilla ,which has the default disk priority 0, fast. The scheduler
should give to mozilla most disk troughput when it needs it.

1) PLEASE CC REPLIES BACK TO ME since I 'm not subscribed to the list (I can't
stand the traffic). However I 'll be checking periodically the list via NNTP.
2) As I have no idea of kernel programming I hope what I propose is aplicable
and relevant to the kernel, as I believe. Sorry if not.
3) I hope what I propose is implementable using the existing scheduler. It would
be nice to have one scheduler to handle them all.
4) I believe that these features don't need a lot of CPU power because the disk
and net I/O troughput are relatively slow.
5) If you think that UNIX tradition forbits what I propose I must say that these
features could be invisible to programs, setting the new priorities to the
default 0 or maybe to the same number as CPU priority.

Thank you very much for your time,

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