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authorAnton Blanchard <anton@samba.org>2012-07-04 16:37:11 -0400
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2012-07-11 00:18:40 -0400
commit18ad51dd342a7eb09dbcd059d0b451b616d4dafc (patch)
tree94809605669eb3b5e4e049501958a2fa93ae2de7 /arch/powerpc/kernel/vdso64/Makefile
parente6a74c6ea331b79c86e1898c504790b3dadc591d (diff)
powerpc: Add VDSO version of getcpu
We have a request for a fast method of getting CPU and NUMA node IDs from userspace. This patch implements a getcpu VDSO function, similar to x86. Ben suggested we use SPRG3 which is userspace readable. SPRG3 can be modified by a KVM guest, so we save the SPRG3 value in the paca and restore it when transitioning from the guest to the host. I have a glibc patch that implements sched_getcpu on top of this. Testing on a POWER7: baseline: 538 cycles vdso: 30 cycles Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/kernel/vdso64/Makefile')
-rw-r--r--arch/powerpc/kernel/vdso64/Makefile2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/vdso64/Makefile b/arch/powerpc/kernel/vdso64/Makefile
index 8c500d8622e4..effca9404b17 100644
--- a/arch/powerpc/kernel/vdso64/Makefile
+++ b/arch/powerpc/kernel/vdso64/Makefile
@@ -1,6 +1,6 @@
1# List of files in the vdso, has to be asm only for now 1# List of files in the vdso, has to be asm only for now
2 2
3obj-vdso64 = sigtramp.o gettimeofday.o datapage.o cacheflush.o note.o 3obj-vdso64 = sigtramp.o gettimeofday.o datapage.o cacheflush.o note.o getcpu.o
4 4
5# Build rules 5# Build rules
6 6