dentries rule. [was: Re: Pros and cons of newer kernels]

Ingo Molnar (
Tue, 18 Nov 1997 16:49:06 +0100 (MET)

On Tue, 18 Nov 1997, Steven N. Hirsch wrote:

> Have _you_ made such a comparison? I have found that /usr/man/man3 is a
> great target for the test. Mine is > 70k and has ~2200 files in it.


'time mc+F10+Enter' in /usr/man/man3 (885 files) on a 32M 100 MHZ P5
system, cached case, non-SMP kernel:

2.0.31: 0.32 user 0.99 system 0:01.43 elapsed 91%CPU

2.1.64: 0.28 user 0.11 system 0:00.48 elapsed 81%CPU

ie. under 2.1, Midnight Commander starts up 3 times faster, time spent in
the kernel is _ten times lower_, ie: dentries rule. The same is true for
'pine' and basically all other applications i use and where interactive
performance matters.

-- mingo

ps. kernel tracing is easy. Just apply the patch sent to linux-kernel a
few days ago by Michael L. Galbraith, turn on 'kernel tracing' in
the 'kernel hacking' options, compile+install the kernel, reboot, run
'doit > trace.txt' and that was it.