Messages in this thread | | | Date | Fri, 28 Mar 2003 16:54:26 -0500 (EST) | From | David Mansfield <> | Subject | Re: very poor performance in 2.5.66[-mm1] |
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On Fri, 28 Mar 2003, Andrew Morton wrote: > > After all of the rave reviews about the interactivity fixes (both regular > > and I/O scheduler related), I decided to give the 2.5.latest a try on my > > desktop machine (system described below) > > > > I started X, everything seemed fine, maybe a bit faster. I opened a > > 'gnome-terminal' and typed 'ls -ltr'. Wow, it was 20x slower. > > > > Here are the timings for 'ls -ltr': > > > > 2.5.66-mm1: 'ls -ltr' 31 seconds > > 2.5.66-mm1: 'ls -ltr | cat' 2 seconds > > 2.4.18-rhlatest: 'ls -ltr' 1.14 seconds > > How many files were there?
1337 files.
> My /usr/bin contains 3168 files. An `ls -ltr' in gnome-terminal takes 9.6 > seconds. In rxvt it takes 0.5 seconds. That's an 850MHz P3. > > So gnome-terminal appears to be a pretty slow application. My guess would be > that something in the 2.5 kernel has exposed a marginality or an outright > bug in it.
Yes. gnome-terminal is godawful slow on RHAT 8.0 (it does Xrender alpha-channel crap for every character to get the anti-aliasing). But I think the problem has to do with the pipe/pty wakeups. After 'ls' writes a line to the pty, it seems as though the gnome-terminal is being woken up (even though 'ls' has more to write), it's generating the Xrender X-command and sending it to X. X is waking up and rendering it (which forces a complete update of the screen).
Under 2.4.18-whatever, it would seem as though 'ls' is generating a large number of lines of output before the gnome-terminal is waking up, causing a dramatically fewer number of redraws.
> It would be interesting to edit include/asm-i386/param.h and set HZ to 100. >
I'll try to check this out over the weekend.
David
-- /==============================\ | David Mansfield | | lkml@dm.cobite.com | \==============================/
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