atomic operations

[Peter Teoh]

in simple terms, any operation, in terms assembly instructions, which can
be executed in ONE instruction, is "atomic", because, just like an atom, it
cannot be broken up into parts.   any instructions that is longer than one,
for eg, TWO instruction, is NOT atomic, because in BETWEEN the first and
2nd instruction, something like an interrupt can come in, and affect the
values of the operand when it is passed from instruction one to second
instruction.  To save me from reiteration:

http://www.ibm.com/developerworks/library/pa-dalign/ (search for
"atomicity").

http://stackoverflow.com/questions/381244/purpose-of-memory-alignment

http://lwn.net/Articles/260832/

http://www.songho.ca/misc/alignment/dataalign.html

http://www.cis.upenn.edu/~palsetia/cit595s08/Lectures08/alignmentOrdering.pdf

Essentially, atomicity and non-alignment become problematic when u tried to
to read using non-byte addressing mode with non-aligned address.

On Sun, Feb 24, 2013 at 5:42 PM, Shraddha Kamat <sh2008ka at gmail.com> wrote:

> what is the relation between atomic operations and memory alignment ?
>
> I read from UTLK that "an unaligned memory access is not atomic"
>
> please explain me , I am not able to get the relationship between
> memory alignment and atomicity of the operation.
>
>
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>



-- 
Regards,
Peter Teoh
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20130224/36c27526/attachment.html