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Diffstat (limited to 'docs/nspr/reference/pr_setconcurrency.rst')
| -rw-r--r-- | docs/nspr/reference/pr_setconcurrency.rst | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/docs/nspr/reference/pr_setconcurrency.rst b/docs/nspr/reference/pr_setconcurrency.rst new file mode 100644 index 0000000000..309a0312bc --- /dev/null +++ b/docs/nspr/reference/pr_setconcurrency.rst @@ -0,0 +1,42 @@ +PR_SetConcurrency +================= + +Creates extra virtual processor threads. Generally used with MP systems. + + +Syntax +------ + +.. code:: + + #include <prinit.h> + + void PR_SetConcurrency(PRUintn numCPUs); + + +Parameter +~~~~~~~~~ + +:ref:`PR_SetConcurrency` has one parameter: + +``numCPUs`` + The number of extra virtual processor threads to be created. + + +Description +----------- + +Setting concurrency controls the number of virtual processors that NSPR +uses to implement its ``M x N`` threading model. The ``M x N`` model is +not available on all host systems. On those where it is not available, +:ref:`PR_SetConcurrency` is ignored. + +Virtual processors are actually\ *global* threads, each of which is +designed to support an arbitrary number of\ *local* threads. Since +global threads are scheduled by the host operating system, this model is +particularly applicable to multiprocessor architectures, where true +parallelism is possible. However, it may also prove advantageous on +uniprocessor systems to reduce the impact of having a locally scheduled +thread calling incidental blocking functions. In such cases, all the +threads being supported by the virtual processor will block, but those +assigned to another virtual processor will be unaffected. |