I'm experimenting with Kernel Preemption

Juan Carlos Castro y Castro jcastro at instant.com.br
Wed May 11 18:28:52 UTC 2005


(I posted this in fedora-list and Rahul Sundaram suggested I post it 
here instead)

Not on Fedora's kernel sources, but with 2.6.11ac7. I based my config on 
/boot/config-2.6.11-1.14_FC3 and dealt with the additional options with 
"make oldconfig". Then I browsed the configuration with "make 
menuconfig", just for fun.

I saw kernel preemption was turned off, so I turned on. Afterwards, I 
notice the system is noticeably faster. Bootup is faster. Shutdown is 
faster. The Red Hat manu on GNOME pops up WAY faster. OpenOffice.org 
loading is faster. I suspect other things are faster too, but I'd have 
to time them.

So my question is: why isn't preemption enabled in the FC3 packaged 
kernel? Does it conflict with something I haven't encountered yet? maybe 
some esoteric hardware combination? My hardware data is below.

Another thing: what crucial patch, if any, am I missing by using 
2.6.11ac7 instead of the FC3 packaged kernel?

[jcastro at ws06 ~]$ cat /proc/cpuinfo
processor       : 0
vendor_id       : AuthenticAMD
cpu family      : 6
model           : 8
model name      : AMD Athlon(tm) XP 2400+
stepping        : 1
cpu MHz         : 1991.906
cache size      : 256 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 1
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge 
mca cmov pat pse36 mmx fxsr sse pni syscall mmxext 3dnowext 3dnow
bogomips        : 3948.54

[jcastro at ws06 ~]$ /sbin/lspci
00:00.0 Host bridge: VIA Technologies, Inc. VT8378 [KM400/A] Chipset 
Host Bridge00:01.0 PCI bridge: VIA Technologies, Inc. VT8237 PCI Bridge
00:10.0 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 
Controller (rev 80)
00:10.1 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 
Controller (rev 80)
00:10.2 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 
Controller (rev 80)
00:10.3 USB Controller: VIA Technologies, Inc. USB 2.0 (rev 82)
00:11.0 ISA bridge: VIA Technologies, Inc. VT8235 ISA Bridge
00:11.1 IDE interface: VIA Technologies, Inc. 
VT82C586A/B/VT82C686/A/B/VT823x/A/C PIPC Bus Master IDE (rev 06)
00:11.5 Multimedia audio controller: VIA Technologies, Inc. 
VT8233/A/8235/8237 AC97 Audio Controller (rev 50)
00:12.0 Ethernet controller: VIA Technologies, Inc. VT6102 [Rhine-II] 
(rev 74)
01:00.0 VGA compatible controller: VIA Technologies, Inc. VT8378 [S3 
UniChrome] Integrated Video (rev 01)




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