[email protected] wrote:
Hello,
By using volatile keyword for spin lock defined by in spinlock_t, it
seems Linux choose to always
reload the value of spin locks from cache instead of using the content
from registers. This may be
helpful for synchronization between multithreads in a single CPU.
I use two Xeon cpus with HyperThreading being disabled on both cpus. I
think the MESI
protocol will enforce the cache coherency and update the spin lock value
automatically between
these two cpus. So maybe we don't need to use the volatile any more, right?
The value must always be loaded from memory. If the value is cached in a
register it will not update when another CPU changes it.
--
Robert Hancock Saskatoon, SK, Canada
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Home Page: http://www.roberthancock.com/
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