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The problem with a Spinlock...
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aminer
Sep 25, 2013, 12:36:54 AM9/25/13
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Hello,
That's not the end of the story, there is still a problem
with the Spinlock with an exponential backoff, i think you have
to undertand something important, the backoff mechanism has
to be set correctly to lower the cache-coherence traffic,
but how to set it correctly ? cause the locked region has
a variable size , so if for example your locked region
takes much more time and it's bigger you have to set the
backoff mechanism with the PAUSE asm instruction(followed by a
sleep(0)) correctly so that it will be bigger than what it
takes to execute the locked region , so this is the problem with
the Spinlocks with backoff , so how can we you do that efficiently?
that's the big question ! and i think it's not easy to do it, for
the lockfree queues, the time to execute a CAS is already known,
so you can set the backoff mechanism of the lockfree queue correctly
so that it become efficient under high contention.
Thank you,
Amine Moulay Ramdane.
That's not the end of the story, there is still a problem
with the Spinlock with an exponential backoff, i think you have
to undertand something important, the backoff mechanism has
to be set correctly to lower the cache-coherence traffic,
but how to set it correctly ? cause the locked region has
a variable size , so if for example your locked region
takes much more time and it's bigger you have to set the
backoff mechanism with the PAUSE asm instruction(followed by a
sleep(0)) correctly so that it will be bigger than what it
takes to execute the locked region , so this is the problem with
the Spinlocks with backoff , so how can we you do that efficiently?
that's the big question ! and i think it's not easy to do it, for
the lockfree queues, the time to execute a CAS is already known,
so you can set the backoff mechanism of the lockfree queue correctly
so that it become efficient under high contention.
Thank you,
Amine Moulay Ramdane.
aminer
Sep 25, 2013, 12:46:44 AM9/25/13
to
I correct a typo, please read again:
Hello,
That's not the end of the story, there is still a problem
with the Spinlock with an exponential backoff, i think you have
to undertand something important, the backoff mechanism has
to be set correctly to lower the cache-coherence traffic,
but how to set it correctly ? cause the locked region has
a variable size , so if for example your locked region
takes much more time and it's bigger you have to set the
backoff mechanism with the PAUSE asm instruction(followed by a
sleep(0)) correctly so that it will be bigger than what it
takes to execute the locked region , so this is the problem with
the Spinlocks with backoff , so how can we you do that efficiently?
that's the big question ! and i think it's not easy to do it, but for
Hello,
That's not the end of the story, there is still a problem
with the Spinlock with an exponential backoff, i think you have
to undertand something important, the backoff mechanism has
to be set correctly to lower the cache-coherence traffic,
but how to set it correctly ? cause the locked region has
a variable size , so if for example your locked region
takes much more time and it's bigger you have to set the
backoff mechanism with the PAUSE asm instruction(followed by a
sleep(0)) correctly so that it will be bigger than what it
takes to execute the locked region , so this is the problem with
the Spinlocks with backoff , so how can we you do that efficiently?
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