kernel-ark/include
Ingo Molnar f8cbd99bd3 [PATCH] sched: voluntary kernel preemption
This patch adds a new preemption model: 'Voluntary Kernel Preemption'.  The
3 models can be selected from a new menu:

            (X) No Forced Preemption (Server)
            ( ) Voluntary Kernel Preemption (Desktop)
            ( ) Preemptible Kernel (Low-Latency Desktop)

we still default to the stock (Server) preemption model.

Voluntary preemption works by adding a cond_resched()
(reschedule-if-needed) call to every might_sleep() check.  It is lighter
than CONFIG_PREEMPT - at the cost of not having as tight latencies.  It
represents a different latency/complexity/overhead tradeoff.

It has no runtime impact at all if disabled.  Here are size stats that show
how the various preemption models impact the kernel's size:

    text    data     bss     dec     hex filename
 3618774  547184  179896 4345854  424ffe vmlinux.stock
 3626406  547184  179896 4353486  426dce vmlinux.voluntary   +0.2%
 3748414  548640  179896 4476950  445016 vmlinux.preempt     +3.5%

voluntary-preempt is +0.2% of .text, preempt is +3.5%.

This feature has been tested for many months by lots of people (and it's
also included in the RHEL4 distribution and earlier variants were in Fedora
as well), and it's intended for users and distributions who dont want to
use full-blown CONFIG_PREEMPT for one reason or another.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-25 16:24:45 -07:00
..
acpi
asm-alpha
asm-arm [PATCH] sched: cleanup context switch locking 2005-06-25 16:24:43 -07:00
asm-arm26
asm-cris
asm-frv
asm-generic
asm-h8300
asm-i386 [PATCH] sched: sched tuning 2005-06-25 16:24:42 -07:00
asm-ia64 [PATCH] sched: cleanup context switch locking 2005-06-25 16:24:43 -07:00
asm-m32r
asm-m68k
asm-m68knommu
asm-mips [PATCH] sched: cleanup context switch locking 2005-06-25 16:24:43 -07:00
asm-parisc
asm-ppc
asm-ppc64 [PATCH] RCU: clean up a few remaining synchronize_kernel() calls 2005-06-25 16:24:38 -07:00
asm-s390 [PATCH] sched: cleanup context switch locking 2005-06-25 16:24:43 -07:00
asm-sh
asm-sh64
asm-sparc [PATCH] sched: cleanup context switch locking 2005-06-25 16:24:43 -07:00
asm-sparc64 [PATCH] sched: cleanup context switch locking 2005-06-25 16:24:43 -07:00
asm-um
asm-v850
asm-x86_64 [PATCH] sched: sched tuning 2005-06-25 16:24:42 -07:00
asm-xtensa
linux [PATCH] sched: voluntary kernel preemption 2005-06-25 16:24:45 -07:00
math-emu
media
mtd
net
pcmcia
rxrpc
scsi
sound
video