serious slowdown in 5.3-BETA1 using SCHED_4BSD and SMP

From: Oliver Lehmann <oliver_at_FreeBSD.org>
Date: Sun, 29 Aug 2004 15:59:45 +0200
Hello,

I've noticed a serious speeddown by using SMP. When I run the same system
with only one CPU, the system works quite well. But after sticking in the
second CPU, the system slows down noticeable. The whole system responds
quite laggy.
That started to happen after I updated FreeBSD from 5.2.1 to 5.3-BETA1. On
5.2.1 I had all kernel debugging options enabled. With that kernel-config
5.3 was not useable in any way. For example playing 128kbit mp3s over nfs
was nearly impossible because it stoped playing every 10-30 seconds for
2-5 seconds....
I did a "ln -s aj /etc/malloc.conf" and disabled all the [DGK]DB, WITNESS*
and INVARIANT* options in my Kernel-config file. IT tokk me 9:52h(!!) to
compile that kernel (make kernel).


Now, booted with that kernel (NUDEL.bak) - SMP feels still much more
slower then 5.2.1 felt.


To show the speeddowns, I built now the attached kernel "NUDEL":

##########################################################################
#### on System: nudel.dmesg
  Booted kernel: "NUDEL.bak" (SCHED_4BSD)
  1 CPU :	 3927.42 real      3279.99 user       454.95 sys
  2 CPUs:	51546.74 real     44414.65 user      5151.46 sys (14hrs!!!)


  Booted kernel: "NUDEL" (SCHED_ULE)
  1 CPU :	 3943.72 real      3284.04 user       459.58 sys
  2 CPUs:	 3864.97 real      3287.69 user       454.52 sys


##########################################################################
#### on System: curry.dmesg
  Booted kernel: "CURRY" (SCHED_4BSD)
  1 CPU :	4376.41 real      3652.60 user       435.60 sys



I built with:

rm -rf /usr/obj/i386-5.3/usr/src/sys/NUDEL && \
/usr/bin/time env MAKEOBJDIRPREFIX=/usr/obj/i386-5.3 make kernel


My make.conf:

KERNCONF?=NUDEL
# MAKEOBJDIRPREFIX=/usr/obj/i386-5.2.1
WRKDIRPREFIX=/usr/obj/${MACHINE}-${OSREL}
#CPUTYPE=p2
# -- use.perl generated deltas -- #
# Created: Fri Mar 21 00:28:26 2003
# Setting to use base perl from ports:
PERL_VER=5.6.1
PERL_VERSION=5.6.1
PERL_ARCH=mach
NOPERL=yo
NO_PERL=yo
NO_PERL_WRAPPER=yo

I've attached the vmstat -i output during make

For example - a simple "make buildworld" with 2CPUs/SCHED_4BSD for (and
on) 5.2.1-RC2 took only 16916.70sec (I'm sorry, but I've no kernel
building times archived)


!!!And it's not just the kernel build - the whole system with running
2 CPUS + SCHED_4BSD is _slow_. I just took the kernel build as an
example!!!

Something seems to be verry broken with SCHED_4BSD+SMP

-- 
 Oliver Lehmann
  http://www.pofo.de/
  http://wishlist.ans-netz.de/
-- 
 Oliver Lehmann
  http://www.pofo.de/
  http://wishlist.ans-netz.de/

Received on Sun Aug 29 2004 - 11:59:52 UTC

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