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| author |   Martin Schwidefsky <schwidefsky@de.ibm.com> | 2015-08-20 12:57:33 +0200 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2015-10-14 14:32:06 +0200 |
| commit | acdc9fc9a8121ce2ebcd7533bd72852c20b353f3 (patch) | |
| tree | b1d501fa146502365256a02ac6aa3352ced890fa | |
| parent | s390/mm: implement soft-dirty bits for user memory change tracking (diff) | |
| download | linux-dev-acdc9fc9a8121ce2ebcd7533bd72852c20b353f3.tar.xz linux-dev-acdc9fc9a8121ce2ebcd7533bd72852c20b353f3.zip | |
s390/bitops: implement cache friendly test_and_set_bit_lock
The generic implementation for test_and_set_bit_lock in include/asm-generic
uses the standard test_and_set_bit operation. This is done with either a
'csg' or a 'loag' instruction. For both version the cache line is fetched
exclusively, even if the bit is already set. The result is an increase in
cache traffic, for a contented lock this is a bad idea.
Acked-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
| -rw-r--r-- | arch/s390/include/asm/bitops.h | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/arch/s390/include/asm/bitops.h b/arch/s390/include/asm/bitops.h index 9b68e98a724f..66a1cff67353 100644 --- a/arch/s390/include/asm/bitops.h +++ b/arch/s390/include/asm/bitops.h @@ -276,6 +276,28 @@ static inline int test_bit(unsigned long nr, const volatile unsigned long *ptr) return (*addr >> (nr & 7)) & 1; } +static inline int test_and_set_bit_lock(unsigned long nr, + volatile unsigned long *ptr) +{ + if (test_bit(nr, ptr)) + return 1; + return test_and_set_bit(nr, ptr); +} + +static inline void clear_bit_unlock(unsigned long nr, + volatile unsigned long *ptr) +{ + smp_mb__before_atomic(); + clear_bit(nr, ptr); +} + +static inline void __clear_bit_unlock(unsigned long nr, + volatile unsigned long *ptr) +{ + smp_mb(); + __clear_bit(nr, ptr); +} + /* * Functions which use MSB0 bit numbering. * On an s390x system the bits are numbered: @@ -446,7 +468,6 @@ static inline int fls(int word) #include <asm-generic/bitops/ffz.h> #include <asm-generic/bitops/find.h> #include <asm-generic/bitops/hweight.h> -#include <asm-generic/bitops/lock.h> #include <asm-generic/bitops/sched.h> #include <asm-generic/bitops/le.h> #include <asm-generic/bitops/ext2-atomic-setbit.h> |