Re: Bad interactive behaviour in 2.5.65-66 (sched.c)

From: Robert Love (rml@tech9.net)
Date: Sat Mar 29 2003 - 18:23:24 EST


On Sat, 2003-03-29 at 16:32, Peter Lundkvist wrote:

> I have seen long delays when starting e.g. xterm from my
> window manager (sawfish) either by keyboard-shortcut or by
> menu command (by mouse) starting from 2.5.65. Sometimes it
> starts immediately, sometimes after up to 2 seconds (idle
> system). If I start a new xterm from xterm it always start
> immediately. 2.5.64 always behaved OK.

You are not alone...

> My first try to solve this problem was to use some
> scheduler parameters from 2.6.64:
> #define MAX_TIMESLICE (300 * HZ / 1000)
> #define CHILD_PENALTY 95
> #define MAX_SLEEP_AVG (2*HZ)
> #define STARVATION_LIMIT (2*HZ)
>
> but got the same behaviour.

Expected.

> 2nd try was to use sched.c, sched.h from 2.5.64 in a
> 2.5.66 build + one line patch in fork.c:
> - p->last_run = jiffies;
> + p->sleep_timestamp = jiffies;
>
> Now the system behaves as it should!

This seems to confirm it was one of the interactivity changes that went
into 2.5.65. I figured as much but it is nice to get confirmation.
Thank you for trying this.

Now to figure out which one...

> My system is a P-III 700 (Inspiron 4000),
> and Debian (X is running at nice = -10).

I wonder if the reniced X is a factor?

        Robert Love

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