Jerry Jiang wrote:
Is there some feedback on this point ?
Thank you
./Jerry
On Sun, 1 Jul 2007 08:49:37 -0400 (EDT)
"Robert P. J. Day" <[email protected]> wrote:
prompted by the earlier post on "volatile"s, is there a reason that
most atomic_t typedefs use volatile int's, while the rest don't?
$ grep "typedef.*struct" $(find . -name atomic.h)
./include/asm-v850/atomic.h:typedef struct { int counter; } atomic_t;
./include/asm-mips/atomic.h:typedef struct { volatile int counter; } atomic_t;
./include/asm-mips/atomic.h:typedef struct { volatile long counter; } atomic64_t;
...
etc, etc. just curious.
If your architecture doesn't support SMP, the volatile keyword doesn't do
anything except add a useless memory fetch. Also, some SMP architectures (i386,
x86_64, s390) provide sufficiently strong guarantees about memory access
ordering that it's not necessary as long as you're using the appropriate
locked/atomic instructions in the atomic operations.
-- Chris
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