RE: MC problem in RH8.0 (Follow-on)

["Maurer, David C" <david c maurer intel com>]

I'm running bash-2.05b on a P-III 733.  I can recreate this on ext2, ext3
and reiserfs filesystems on three different machines.

I can start to see the slowdown on 5 to 6 directories, and it appears that
the longer the directory name is and the further down in the subdirectory
level you are, the worse the slowdown becomes.

I did try running mc -u to disable the concurrent subshells, and this did
eliminate the slowdown completely!!!  I then turned on subshell support
again, created a 7-level directory structure with 30 character directory
names.  The slowdown was roughly 5 seconds between changing from the bottom
of one directory chain to someplace else.  I had top running concurrently,
and it showed that the spawned bash session created for the subshell spiked
to ~95% cpu usage while changing directories (This was on my 733 machine).

I have also duplicated this issue on two other machines with RedHat 8.0
stock installations.  One is an AMD Duron 700, the other is a Pentium III-M
1GHz.  The first machine I was running the tests on is a P-III 733.  The AMD
was the slowest, followed by the 733, then the 1GHz.  All three have the the
same ammount of SDRAM.  The 1GHz machine only showed a %15 cpu usage from
the bash subshell, and the 733 and AMD pegged the CPU.  The only differnce
between the 1GHz and 733MHz machines is the on-die cache size 512k vs 256k.
The Duron only has 192k.  This may suggest some thrashing going on in the
subshell.

-----Original Message-----
From: Pavel Roskin [mailto:proski gnu org]
Sent: Friday, October 18, 2002 12:33 PM
To: Maurer, David C
Cc: mc gnome org
Subject: Re: MC problem in RH8.0 (Follow-on)


Hello!

> The slowdown a is noticibly dramatic change from RH 7.3 to RH 8.0.  It
feels
> like it's griding to a halt when changing directories (even ones with no
> files in it), but not the type of delay associated with sorting a
directory
> with 1000s of files in it.

I could not reproduce it on Red Hat 8.0.  I tried to reproduce it on tmpfs
and reiserfs by creating long chains of directories.  My subshell is bash
2.05b from Red Hat.

What filesystem do you use?  What is the directory name?  I just don't
know how many levels you need (hundreds, thousands).  Please try running
mc without subshell support: "mc -u" - maybe it will work faster.  What
shell are you using?

Are you running nscd?  Try running or killing it and check if it makes any 
difference.  Are you using any centralized user database, like NIS?

> This change directory slowdown occurs both when tabbing from one window
> to the other, but changing directories from within the same window, and
> changing directories from the command line with the cd / command.  To me
> this points to a problem with a RH 8.0 library somewhere mc is linking
> to. But this is purely speculation.

I don't know.  To me it sounds more like a filesystem bug or a bug in the
subshell support (or may be in the subshell itself).

The latest versions of Valgrind (http://developer.kde.org/~sewardj/)  
include a profiler.  Maybe you could try using it to find where mc spends 
most of the time?

-- 
Regards,
Pavel Roskin

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