22 Jun
2011
22 Jun
'11
2:34 p.m.
On 06/21/2011 09:03 PM, Ralf Mardorf wrote:
Hi,
could there be any disadvantages for averaged desktop users, server
usage etc., if the kernel 2.6.39 is build as PREEMPT kernel?
Today I installed the kernel from the repositories of a major Distro:
$ uname -a
Linux debian 2.6.39-2-amd64 #1 SMP Wed Jun 8 11:01:04 UTC 2011 x86_64
GNU/Linux
Some time ago I build the kernel myself:
$ uname -a
Linux debian 2.6.39.1 #1 SMP PREEMPT Tue Jun 7 01:40:05 CEST 2011 x86_64
GNU/Linux
I'm asking, because I want to know, if it would be reasonable to appeal,
that major distros should build it as PREEMPT kernel.
Well, they should offer the option (a kernel-flavor - compare to -bigmem
or -xen, or -vserver, etc). but as default: no.
Preemptive scheduling introduces some overhead [for each process] and
effectively reduces throughput.
As the vast majority of systems (both Desktop and Server) do not run any
processes with SCHED_FF or use elevated scheduling priorities. Thus
there is no benefit and only drawbacks (the machine is a tiny-bit slower
and consumes more power with a PREEMPT kernel).
robin