diff options
| author | Anton Blanchard <[email protected]> | 2012-07-04 20:37:11 +0000 |
|---|---|---|
| committer | Benjamin Herrenschmidt <[email protected]> | 2012-07-11 14:18:40 +1000 |
| commit | 18ad51dd342a7eb09dbcd059d0b451b616d4dafc (patch) | |
| tree | 94809605669eb3b5e4e049501958a2fa93ae2de7 /tools/perf/util/trace-event-scripting.c | |
| parent | e6a74c6ea331b79c86e1898c504790b3dadc591d (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 <[email protected]>
Signed-off-by: Benjamin Herrenschmidt <[email protected]>
Diffstat (limited to 'tools/perf/util/trace-event-scripting.c')
0 files changed, 0 insertions, 0 deletions