Hi Santosh,
Le 26/08/2019 à 07:44, Santosh Sivaraj a écrit :
Hi Christophe,
Christophe Leroy <christophe.le...@c-s.fr> writes:
__get_datapage() is only a few instructions to retrieve the
address of the page where the kernel stores data to the VDSO.
By inlining this function into its users, a bl/blr pair and
a mflr/mtlr pair is avoided, plus a few reg moves.
The improvement is noticeable (about 55 nsec/call on an 8xx)
vdsotest before the patch:
gettimeofday: vdso: 731 nsec/call
clock-gettime-realtime-coarse: vdso: 668 nsec/call
clock-gettime-monotonic-coarse: vdso: 745 nsec/call
vdsotest after the patch:
gettimeofday: vdso: 677 nsec/call
clock-gettime-realtime-coarse: vdso: 613 nsec/call
clock-gettime-monotonic-coarse: vdso: 690 nsec/call
Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
arch/powerpc/kernel/vdso32/cacheflush.S | 10 +++++-----
arch/powerpc/kernel/vdso32/datapage.S | 29 ++++-------------------------
arch/powerpc/kernel/vdso32/datapage.h | 11 +++++++++++
arch/powerpc/kernel/vdso32/gettimeofday.S | 13 ++++++-------
4 files changed, 26 insertions(+), 37 deletions(-)
create mode 100644 arch/powerpc/kernel/vdso32/datapage.h
The datapage.h file should ideally be moved under include/asm, then we can use
the same for powerpc64 too.
I have a more ambitious project indeed.
Most of the VDSO code is duplicated between vdso32 and vdso64. I'm
aiming at merging everything into a single source code.
This means we would have to generate vdso32.so and vdso64.so out of the
same source files. Any idea on how to do that ? I'm not too good at
creating Makefiles. I guess we would have everything in
arch/powerpc/kernel/vdso/ and would have to build the objects twice,
once in arch/powerpc/kernel/vdso32/ and once in arch/powerpc/kernel/vdso64/
Christophe
