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42 lines
1.2 KiB
ReStructuredText
42 lines
1.2 KiB
ReStructuredText
PR_SetConcurrency
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=================
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Creates extra virtual processor threads. Generally used with MP systems.
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Syntax
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------
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.. code::
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#include <prinit.h>
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void PR_SetConcurrency(PRUintn numCPUs);
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Parameter
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~~~~~~~~~
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:ref:`PR_SetConcurrency` has one parameter:
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``numCPUs``
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The number of extra virtual processor threads to be created.
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Description
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-----------
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Setting concurrency controls the number of virtual processors that NSPR
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uses to implement its ``M x N`` threading model. The ``M x N`` model is
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not available on all host systems. On those where it is not available,
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:ref:`PR_SetConcurrency` is ignored.
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Virtual processors are actually\ *global* threads, each of which is
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designed to support an arbitrary number of\ *local* threads. Since
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global threads are scheduled by the host operating system, this model is
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particularly applicable to multiprocessor architectures, where true
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parallelism is possible. However, it may also prove advantageous on
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uniprocessor systems to reduce the impact of having a locally scheduled
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thread calling incidental blocking functions. In such cases, all the
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threads being supported by the virtual processor will block, but those
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assigned to another virtual processor will be unaffected.
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