Re: solved (was Re: xterm scrolling speed - scheduling weirdness in 2.6 ?!)

[Tim Connors <tconnors+linuxkernel1080970205@astro.swin.edu.au>]

Soeren Sonnenburg <kernel@nn7.de> said on Fri, 02 Apr 2004 20:22:12 +0200:
> On Mon, 2004-01-05 at 10:50, Kenneth Johansson wrote:
> > On Mon, 2004-01-05 at 00:47, Mike Fedyk wrote:
> > > On Mon, Jan 05, 2004 at 12:33:12AM +0100, Willy Tarreau wrote:
> > > > at a time. I have yet to understand why 'ls|cat' behaves
> > > > differently, but fortunately it works and it has already saved
> > > > me some useful time.
> > > 
> > > cat probably does some buffering for you, and sends the output to xterm in
> > > larger blocks.
> > 
> > you can try with "ls |dd bs=1"
> > 
> > I also see this problem but it is not constant. I noticed that "ps ax"
> > sometimes takes like 10 times longer than usual. But I can only get this
> > in a gnome-terminal not in xterm. The problem is that it should really
> > not be that big difference when the load of the system is the same. 
> 
> Ok, there is indeed an issue in the *terminals. As above pointed out
> buffering the programs output helps. Also a usleep of 5ms in the read
> loop of the *terms would help.
> 
> I fixed this issue in multi-gnome-terminal by using a buffer of 32kb.
> It is filled as long as there is input comming in within 10ms.
> If the buffer is full or 10ms passed the buffer is written out to the
> screen. This makes it also 2-3 times faster on kernel 2.4.

A factor of 2 or 3 though?

In 2.4, to ls -lA my home directory with its 510 files, took less than
0.5 sec. Currently, buffering via cat in 2.6 takes 0.5 sec. Just
straight ls -lA takes 6 seconds or so.

Does your factor of 3 bring you up to what you were seeing in 2.4, or
do you still have a regression?

-- 
TimC -- http://astronomy.swin.edu.au/staff/tconnors/
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