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由 Sebastian Sanchez 提交于
Currently the driver doesn't support completion vectors. These are used to indicate which sets of CQs should be grouped together into the same vector. A vector is a CQ processing thread that runs on a specific CPU. If an application has several CQs bound to different completion vectors, and each completion vector runs on different CPUs, then the completion queue workload is balanced. This helps scale as more nodes are used. Implement CQ completion vector support using a global workqueue where a CQ entry is queued to the CPU corresponding to the CQ's completion vector. Since the workqueue is global, it's guaranteed to always be there when queueing CQ entries; Therefore, the RCU locking for cq->rdi->worker in the hot path is superfluous. Each completion vector is assigned to a different CPU. The number of completion vectors available is computed by taking the number of online, physical CPUs from the local NUMA node and subtracting the CPUs used for kernel receive queues and the general interrupt. Special use cases: * If there are no CPUs left for completion vectors, the same CPU for the general interrupt is used; Therefore, there would only be one completion vector available. * For multi-HFI systems, the number of completion vectors available for each device is the total number of completion vectors in the local NUMA node divided by the number of devices in the same NUMA node. If there's a division remainder, the first device to get initialized gets an extra completion vector. Upon a CQ creation, an invalid completion vector could be specified. Handle it as follows: * If the completion vector is less than 0, set it to 0. * Set the completion vector to the result of the passed completion vector moded with the number of device completion vectors available. Reviewed-by: NMike Marciniszyn <mike.marciniszyn@intel.com> Signed-off-by: NSebastian Sanchez <sebastian.sanchez@intel.com> Signed-off-by: NDennis Dalessandro <dennis.dalessandro@intel.com> Signed-off-by: NDoug Ledford <dledford@redhat.com>
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