When looking through some instruction traces I noticed our tracepoint
checks were inline. It turns out we don't have CONFIG_JUMP_LABEL
enabled.
By enabling CONFIG_JUMP_LABEL we replace a load/compare/branch with
a nop at every tracepoint call. For example in do_IRQ:
CONFIG_JUMP_LABEL disabled:
stdx 3,11,9
lwz 0,8(29)
cmpwi 7,0,0
bne- 7,.L124
bl .irq_enter
CONFIG_JUMP_LABEL enabled:
stdx 3,11,9
nop
bl .irq_enter
Signed-off-by: Anton Blanchard <an...@samba.org>
---
Index: linux-build/arch/powerpc/configs/ppc64_defconfig
===================================================================
--- linux-build.orig/arch/powerpc/configs/ppc64_defconfig 2012-04-05
13:47:45.691857096 +1000
+++ linux-build/arch/powerpc/configs/ppc64_defconfig 2012-05-23
13:14:04.254270594 +1000
@@ -16,6 +16,7 @@ CONFIG_BLK_DEV_INITRD=y
CONFIG_PROFILING=y
CONFIG_OPROFILE=y
CONFIG_KPROBES=y
+CONFIG_JUMP_LABEL=y
CONFIG_MODULES=y
CONFIG_MODULE_UNLOAD=y
CONFIG_MODVERSIONS=y
Index: linux-build/arch/powerpc/configs/pseries_defconfig
===================================================================
--- linux-build.orig/arch/powerpc/configs/pseries_defconfig 2012-04-05
13:47:45.691857096 +1000
+++ linux-build/arch/powerpc/configs/pseries_defconfig 2012-05-23
13:14:59.783222304 +1000
@@ -24,6 +24,7 @@ CONFIG_BLK_DEV_INITRD=y
CONFIG_PROFILING=y
CONFIG_OPROFILE=y
CONFIG_KPROBES=y
+CONFIG_JUMP_LABEL=y
CONFIG_MODULES=y
CONFIG_MODULE_UNLOAD=y
CONFIG_MODVERSIONS=y
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
