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Date: Mon, 2 Sep 2002 15:54:07 +0200 (CEST)
From: Tobias Ringstrom <tori@ringstrom.mine.nu>
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To: Ingo Molnar <mingo@elte.hu>
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Subject: Re: Problem with the O(1) scheduler in 2.4.19
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On Mon, 2 Sep 2002, Ingo Molnar wrote:

> On Sun, 1 Sep 2002, Tobias Ringstrom wrote:
> 
> > While the O(1) scheduler has performed very well for me in most
> > situations, I have one big problem with it.  When running a
> > Counter-Strike game server on Linux 2.4.19 with the sched-2.4.19-rc2-A4
> > patch applied, the server process is niced from the default value of 15
> > (interactive) to 25 (background).  This means that every time crond
> > wakes up or a mail arrives the game latency becomes extremely bad and
> > the users experience lag.
> 
> does the same problem happen if you renice the game server to -10 or -15?

The process was at nice level 0, which I think corresponds to prio 15-25
for interactive to background tasks if I understand things correctly.  
When I used top to renice the process to -10, the prio became 15, i.e. it
was still considered non-interactive.  I even tried -20 (or maybe -19),
and it was still at the non-interactive prio.

In other words:  For all nice values I tried (-20, -10, 0), the prio was
20+nice+5.  When the server is lightly loaded, the prio is 20+nice-5.

Note that even when the server was loaded, it only used 70% CPU, which I
suppose must mean that it does not use up the time slices, which I thought
should make the kernel treat the process as interactive.  Is there a
description of the criteria somewhere (other than in the source code)?

/Tobias

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