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| author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2013-09-18 11:45:36 +0200 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2013-10-24 17:16:55 +0200 |
| commit | 746479cdcbb131a0645e8cb4a35d6b26126e3e4c (patch) | |
| tree | 7cf0fa041804197c14abe21c56bdf27c82274718 /arch/s390/Kconfig | |
| parent | 8e6a8285668b139460cc6852bfd58fdbd00c7157 (diff) | |
| download | lwn-746479cdcbb131a0645e8cb4a35d6b26126e3e4c.tar.gz lwn-746479cdcbb131a0645e8cb4a35d6b26126e3e4c.zip | |
s390/bitops: use generic find bit functions / reimplement _left variant
Just like all other architectures we should use out-of-line find bit
operations, since the inline variant bloat the size of the kernel image.
And also like all other architecures we should only supply optimized
variants of the __ffs, ffs, etc. primitives.
Therefore this patch removes the inlined s390 find bit functions and uses
the generic out-of-line variants instead.
The optimization of the primitives follows with the next patch.
With this patch also the functions find_first_bit_left() and
find_next_bit_left() have been reimplemented, since logically, they are
nothing else but a find_first_bit()/find_next_bit() implementation that
use an inverted __fls() instead of __ffs().
Also the restriction that these functions only work on machines which
support the "flogr" instruction is gone now.
This reduces the size of the kernel image (defconfig, -march=z9-109)
by 144,482 bytes.
Alone the size of the function build_sched_domains() gets reduced from
7 KB to 3,5 KB.
We also git rid of unused functions like find_first_bit_le()...
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/Kconfig')
| -rw-r--r-- | arch/s390/Kconfig | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 7143793859fa..a02177fb5ec1 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -99,6 +99,7 @@ config S390 select CLONE_BACKWARDS2 select GENERIC_CLOCKEVENTS select GENERIC_CPU_DEVICES if !SMP + select GENERIC_FIND_FIRST_BIT select GENERIC_SMP_IDLE_THREAD select GENERIC_TIME_VSYSCALL_OLD select HAVE_ALIGNED_STRUCT_PAGE if SLUB |