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[Xen-changelog] Remove CONFIG_PREEMPT configuration option from Xen kernel builds.



# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID f887ddae2b03ab363278afc92225aa3bc320de5f
# Parent  877d738e7a4005bee085bb42341b9d754e8eb978
Remove CONFIG_PREEMPT configuration option from Xen kernel builds.
The option reduces overall system performance and makes little sense
when running over a preemptive hypervisor. Removing the option also
fixes some hypothetical races.

The forthcoming voluntary-preemption option will make much more sense
to enable when running over Xen.

Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>

diff -r 877d738e7a40 -r f887ddae2b03 
linux-2.6-xen-sparse/arch/xen/configs/xen0_defconfig_x86_32
--- a/linux-2.6-xen-sparse/arch/xen/configs/xen0_defconfig_x86_32       Thu Nov 
24 18:49:15 2005
+++ b/linux-2.6-xen-sparse/arch/xen/configs/xen0_defconfig_x86_32       Thu Nov 
24 19:01:16 2005
@@ -35,7 +35,6 @@
 # CONFIG_CLEAN_COMPILE is not set
 CONFIG_BROKEN=y
 CONFIG_BROKEN_ON_SMP=y
-CONFIG_LOCK_KERNEL=y
 CONFIG_INIT_ENV_ARG_LIMIT=32
 
 #
@@ -125,8 +124,6 @@
 # CONFIG_HPET_TIMER is not set
 # CONFIG_HPET_EMULATE_RTC is not set
 # CONFIG_SMP is not set
-CONFIG_PREEMPT=y
-CONFIG_PREEMPT_BKL=y
 # CONFIG_X86_REBOOTFIXUPS is not set
 CONFIG_MICROCODE=y
 CONFIG_X86_CPUID=y
@@ -141,7 +138,6 @@
 # CONFIG_HIGHMEM64G is not set
 CONFIG_HIGHMEM=y
 CONFIG_MTRR=y
-CONFIG_HAVE_DEC_LOCK=y
 # CONFIG_REGPARM is not set
 CONFIG_X86_LOCAL_APIC=y
 CONFIG_X86_IO_APIC=y
@@ -1259,7 +1255,6 @@
 CONFIG_LOG_BUF_SHIFT=14
 # CONFIG_SCHEDSTATS is not set
 # CONFIG_DEBUG_SLAB is not set
-# CONFIG_DEBUG_PREEMPT is not set
 # CONFIG_DEBUG_SPINLOCK is not set
 # CONFIG_DEBUG_SPINLOCK_SLEEP is not set
 # CONFIG_DEBUG_KOBJECT is not set
diff -r 877d738e7a40 -r f887ddae2b03 
linux-2.6-xen-sparse/arch/xen/configs/xen0_defconfig_x86_64
--- a/linux-2.6-xen-sparse/arch/xen/configs/xen0_defconfig_x86_64       Thu Nov 
24 18:49:15 2005
+++ b/linux-2.6-xen-sparse/arch/xen/configs/xen0_defconfig_x86_64       Thu Nov 
24 19:01:16 2005
@@ -90,7 +90,6 @@
 CONFIG_X86_GOOD_APIC=y
 # CONFIG_HPET_TIMER is not set
 # CONFIG_SMP is not set
-# CONFIG_PREEMPT is not set
 CONFIG_MICROCODE=y
 # CONFIG_X86_CPUID is not set
 CONFIG_SWIOTLB=y
diff -r 877d738e7a40 -r f887ddae2b03 
linux-2.6-xen-sparse/arch/xen/configs/xenU_defconfig_x86_32
--- a/linux-2.6-xen-sparse/arch/xen/configs/xenU_defconfig_x86_32       Thu Nov 
24 18:49:15 2005
+++ b/linux-2.6-xen-sparse/arch/xen/configs/xenU_defconfig_x86_32       Thu Nov 
24 19:01:16 2005
@@ -125,8 +125,6 @@
 CONFIG_SMP_ALTERNATIVES=y
 CONFIG_NR_CPUS=8
 # CONFIG_SCHED_SMT is not set
-CONFIG_PREEMPT=y
-CONFIG_PREEMPT_BKL=y
 # CONFIG_X86_REBOOTFIXUPS is not set
 CONFIG_X86_CPUID=y
 
@@ -550,7 +548,6 @@
 CONFIG_LOG_BUF_SHIFT=14
 # CONFIG_SCHEDSTATS is not set
 # CONFIG_DEBUG_SLAB is not set
-# CONFIG_DEBUG_PREEMPT is not set
 # CONFIG_DEBUG_SPINLOCK is not set
 # CONFIG_DEBUG_SPINLOCK_SLEEP is not set
 # CONFIG_DEBUG_KOBJECT is not set
diff -r 877d738e7a40 -r f887ddae2b03 
linux-2.6-xen-sparse/arch/xen/configs/xenU_defconfig_x86_64
--- a/linux-2.6-xen-sparse/arch/xen/configs/xenU_defconfig_x86_64       Thu Nov 
24 18:49:15 2005
+++ b/linux-2.6-xen-sparse/arch/xen/configs/xenU_defconfig_x86_64       Thu Nov 
24 19:01:16 2005
@@ -92,7 +92,6 @@
 CONFIG_SMP=y
 CONFIG_NR_CPUS=8
 # CONFIG_SCHED_SMT is not set
-# CONFIG_PREEMPT is not set
 # CONFIG_MICROCODE is not set
 CONFIG_X86_CPUID=y
 # CONFIG_NUMA is not set
diff -r 877d738e7a40 -r f887ddae2b03 
linux-2.6-xen-sparse/arch/xen/configs/xen_defconfig_x86_32
--- a/linux-2.6-xen-sparse/arch/xen/configs/xen_defconfig_x86_32        Thu Nov 
24 18:49:15 2005
+++ b/linux-2.6-xen-sparse/arch/xen/configs/xen_defconfig_x86_32        Thu Nov 
24 19:01:16 2005
@@ -132,8 +132,6 @@
 CONFIG_SMP_ALTERNATIVES=y
 CONFIG_NR_CPUS=8
 # CONFIG_SCHED_SMT is not set
-CONFIG_PREEMPT=y
-CONFIG_PREEMPT_BKL=y
 # CONFIG_X86_REBOOTFIXUPS is not set
 CONFIG_MICROCODE=y
 CONFIG_X86_CPUID=m
@@ -2951,7 +2949,6 @@
 CONFIG_LOG_BUF_SHIFT=14
 # CONFIG_SCHEDSTATS is not set
 # CONFIG_DEBUG_SLAB is not set
-CONFIG_DEBUG_PREEMPT=y
 # CONFIG_DEBUG_SPINLOCK is not set
 # CONFIG_DEBUG_SPINLOCK_SLEEP is not set
 # CONFIG_DEBUG_KOBJECT is not set
diff -r 877d738e7a40 -r f887ddae2b03 
linux-2.6-xen-sparse/arch/xen/configs/xen_defconfig_x86_64
--- a/linux-2.6-xen-sparse/arch/xen/configs/xen_defconfig_x86_64        Thu Nov 
24 18:49:15 2005
+++ b/linux-2.6-xen-sparse/arch/xen/configs/xen_defconfig_x86_64        Thu Nov 
24 19:01:16 2005
@@ -95,7 +95,6 @@
 CONFIG_SMP=y
 CONFIG_NR_CPUS=8
 # CONFIG_SCHED_SMT is not set
-# CONFIG_PREEMPT is not set
 CONFIG_MICROCODE=y
 # CONFIG_X86_CPUID is not set
 # CONFIG_NUMA is not set
diff -r 877d738e7a40 -r f887ddae2b03 linux-2.6-xen-sparse/arch/xen/i386/Kconfig
--- a/linux-2.6-xen-sparse/arch/xen/i386/Kconfig        Thu Nov 24 18:49:15 2005
+++ b/linux-2.6-xen-sparse/arch/xen/i386/Kconfig        Thu Nov 24 19:01:16 2005
@@ -415,17 +415,17 @@
          cost of slightly increased overhead in some places. If unsure say
          N here.
 
-config PREEMPT
-       bool "Preemptible Kernel"
-       help
-         This option reduces the latency of the kernel when reacting to
-         real-time or interactive events by allowing a low priority process to
-         be preempted even if it is in kernel mode executing a system call.
-         This allows applications to run more reliably even when the system is
-         under load.
-
-         Say Y here if you are building a kernel for a desktop, embedded
-         or real-time system.  Say N if you are unsure.
+#config PREEMPT
+#      bool "Preemptible Kernel"
+#      help
+#        This option reduces the latency of the kernel when reacting to
+#        real-time or interactive events by allowing a low priority process to
+#        be preempted even if it is in kernel mode executing a system call.
+#        This allows applications to run more reliably even when the system is
+#        under load.
+#
+#        Say Y here if you are building a kernel for a desktop, embedded
+#        or real-time system.  Say N if you are unsure.
 
 config PREEMPT_BKL
        bool "Preempt The Big Kernel Lock"
diff -r 877d738e7a40 -r f887ddae2b03 
linux-2.6-xen-sparse/arch/xen/x86_64/Kconfig
--- a/linux-2.6-xen-sparse/arch/xen/x86_64/Kconfig      Thu Nov 24 18:49:15 2005
+++ b/linux-2.6-xen-sparse/arch/xen/x86_64/Kconfig      Thu Nov 24 19:01:16 2005
@@ -224,21 +224,21 @@
 
          If you don't know what to do here, say N.
 
-config PREEMPT
-       bool "Preemptible Kernel"
-       ---help---
-         This option reduces the latency of the kernel when reacting to
-         real-time or interactive events by allowing a low priority process to
-         be preempted even if it is in kernel mode executing a system call.
-         This allows applications to run more reliably even when the system is
-         under load. On contrary it may also break your drivers and add
-         priority inheritance problems to your system. Don't select it if
-         you rely on a stable system or have slightly obscure hardware.
-         It's also not very well tested on x86-64 currently.
-         You have been warned.
-
-         Say Y here if you are feeling brave and building a kernel for a
-         desktop, embedded or real-time system.  Say N if you are unsure.
+#config PREEMPT
+#      bool "Preemptible Kernel"
+#      ---help---
+#        This option reduces the latency of the kernel when reacting to
+#        real-time or interactive events by allowing a low priority process to
+#        be preempted even if it is in kernel mode executing a system call.
+#        This allows applications to run more reliably even when the system is
+#        under load. On contrary it may also break your drivers and add
+#        priority inheritance problems to your system. Don't select it if
+#        you rely on a stable system or have slightly obscure hardware.
+#        It's also not very well tested on x86-64 currently.
+#        You have been warned.
+#
+#        Say Y here if you are feeling brave and building a kernel for a
+#        desktop, embedded or real-time system.  Say N if you are unsure.
 
 config SCHED_SMT
        bool "SMT (Hyperthreading) scheduler support"

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