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| author | Jiri Kosina <jkosina@suse.cz> | 2012-04-08 21:48:52 +0200 |
|---|---|---|
| committer | Jiri Kosina <jkosina@suse.cz> | 2012-04-08 21:48:52 +0200 |
| commit | e75d660672ddd11704b7f0fdb8ff21968587b266 (patch) | |
| tree | ccb9c107744c10b553c0373e450bee3971d16c00 /arch/Kconfig | |
| parent | 61282f37927143e45b03153f3e7b48d6b702147a (diff) | |
| parent | 0034102808e0dbbf3a2394b82b1bb40b5778de9e (diff) | |
Merge branch 'master' into for-next
Merge with latest Linus' tree, as I have incoming patches
that fix code that is newer than current HEAD of for-next.
Conflicts:
drivers/net/ethernet/realtek/r8169.c
Diffstat (limited to 'arch/Kconfig')
| -rw-r--r-- | arch/Kconfig | 33 |
1 files changed, 25 insertions, 8 deletions
diff --git a/arch/Kconfig b/arch/Kconfig index 4f55c736be1..684eb5af439 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -47,18 +47,29 @@ config KPROBES If in doubt, say "N". config JUMP_LABEL - bool "Optimize trace point call sites" + bool "Optimize very unlikely/likely branches" depends on HAVE_ARCH_JUMP_LABEL help + This option enables a transparent branch optimization that + makes certain almost-always-true or almost-always-false branch + conditions even cheaper to execute within the kernel. + + Certain performance-sensitive kernel code, such as trace points, + scheduler functionality, networking code and KVM have such + branches and include support for this optimization technique. + If it is detected that the compiler has support for "asm goto", - the kernel will compile trace point locations with just a - nop instruction. When trace points are enabled, the nop will - be converted to a jump to the trace function. This technique - lowers overhead and stress on the branch prediction of the - processor. + the kernel will compile such branches with just a nop + instruction. When the condition flag is toggled to true, the + nop will be converted to a jump instruction to execute the + conditional block of instructions. - On i386, options added to the compiler flags may increase - the size of the kernel slightly. + This technique lowers overhead and stress on the branch prediction + of the processor and generally makes the kernel faster. The update + of the condition is slower, but those are always very rare. + + ( On 32-bit x86, the necessary options added to the compiler + flags may increase the size of the kernel slightly. ) config OPTPROBES def_bool y @@ -109,6 +120,9 @@ config HAVE_KRETPROBES config HAVE_OPTPROBES bool + +config HAVE_NMI_WATCHDOG + bool # # An arch should select this if it provides all these things: # @@ -199,4 +213,7 @@ config HAVE_CMPXCHG_LOCAL config HAVE_CMPXCHG_DOUBLE bool +config ARCH_WANT_OLD_COMPAT_IPC + bool + source "kernel/gcov/Kconfig" |