From: Con Kolivas <kernel@kolivas.org>
To: Willy Tarreau <willy@w.ods.org>
Subject: Re: xterm scrolling speed - scheduling weirdness in 2.6 ?!
Date: Sun, 4 Jan 2004 12:42:47 +1100
User-Agent: KMail/1.5.3
Cc: Soeren Sonnenburg <kernel@nn7.de>, Mark Hahn <hahn@physics.mcmaster.ca>,
       Linux Kernel <linux-kernel@vger.kernel.org>, gillb4@telusplanet.net
References: <Pine.LNX.4.44.0401031439060.24942-100000@coffee.psychology.mcmaster.ca> <200401040815.54655.kernel@kolivas.org> <20040103233518.GE3728@alpha.home.local>
In-Reply-To: <20040103233518.GE3728@alpha.home.local>
MIME-Version: 1.0
Content-Type: text/plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
Message-Id: <200401041242.47410.kernel@kolivas.org>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1461
Lines: 34

On Sun, 4 Jan 2004 10:35, Willy Tarreau wrote:
> 6) Conclusion
> =============
>
> Under 2.4, xterm uses jump scrolling which it does not use by default under
> 2.6 if X responds fast enough. The first dirty solution which comes to mind
> is to renice X to >+10 to slow it a bit so that xterm hits the high water
> level and jumps.
>
> But it's not an effect of the scheduler alone, but a side effect of the
> scheduler and xterm both trying to automatically adjust their behaviour in
> a different manner. 

Not quite. The scheduler retains high priority for X for longer so it's no new 
dynamic adjustment of any sort, just better cpu usage by X (which is why it's 
smoother now at nice 0 than previously). 

> If either the scheduler or xterm was a bit smarter or 
> used different thresholds, the problem would go away. It would also explain
> why there are people who cannot reproduce it. Perhaps a somewhat faster or
> slower system makes the problem go away. Honnestly, it's the first time
> that I notice that my xterms are jump-scrolling, it was so much fluid
> anyway.

Very thorough but not a scheduler problem as far as I'm concerned. Can you not 
disable smooth scrolling and force jump scrolling?

Con

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/