Messages in this thread | | | From | <> | Subject | Volatile vs Non-Volatile Spin Locks on SMP. | Date | Fri, 15 Jul 2005 12:22:31 -0700 |
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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?
Based on this, I rebuilt the Intel e1000 Gigabit network card driver with volatile being removed, but I didn't notice any performance improvement.
Any idea about this,
Thanks a lot,
Liang
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