Abstract: There is broadly contemplated herein an arrangement whereby each event source feeds a small dedicated “pre-counter” while an actual count is kept in a 64-bit wide RAM. Such an implementation preferably may involve a state machine that simply sweeps through the pre-counters, in a predetermined fixed order. Preferably, the state machine will access each pre-counter, add the value from the pre-counter to a corresponding RAM location, and then clear the pre-counter. Accordingly, the pre-counters merely have to be wide enough such that even at a maximal event rate, the pre-counter will not be able to wrap (i.e., reach capacity or overflow) before the “sweeper” state machine accesses the pre-counter.

Abstract: There is broadly contemplated herein an arrangement whereby each event source feeds a small dedicated “pre-counter” while an actual count is kept in a 64-bit wide RAM. Such an implementation preferably may involve a state machine that simply sweeps through the pre-counters, in a predetermined fixed order. Preferably, the state machine will access each pre-counter, add the value from the pre-counter to a corresponding RAM location, and then clear the pre-counter. Accordingly, the pre-counters merely have to be wide enough such that even at a maximal event rate, the pre-counter will not be able to wrap (i.e., reach capacity or overflow) before the “sweeper” state machine accesses the pre-counter.

Abstract: A mechanism for temporarily stalling selected Direct Memory Access (DMA) operations in a physical input/output (I/O) adapter in order to permit migration of data between physical pages that are subject to access by the physical I/O adapter. When a request for a DMA to a physical page in system memory is received from an I/O adapter, a migration in progress (MIP) bit in a translation control entry (TCE) pointing to the physical page is examined, wherein the MIP bit indicates whether migration of the physical page referenced in the TCE to another location in system memory is currently in progress. If the MIP bit indicates a migration of the physical page is in progress, the DMA from the I/O adapter is temporarily stalled while other DMA operations from other I/O adapters to other physical pages in system memory are allowed to continue.

Abstract: A computer-implemented method, apparatus, and computer program product are disclosed for migrating data from a source physical page to a destination physical page. A migration process is begun to migrate data from the source physical page to the destination physical page which causes a host bridge to enter a first state. The host bridge then suspends processing of direct memory access operations when the host bridge is in the first state. The data is migrated from the source physical page to the destination physical page while the host bridge is in the first state.

Abstract: There is broadly contemplated herein an arrangement whereby each event source feeds a small dedicated “pre-counter” while an actual count is kept in a 64-bit wide RAM. Such an implementation preferably may involve a state machine that simply sweeps through the pre-counters, in a predetermined fixed order. Preferably, the state machine will access each pre-counter, add the value from the pre-counter to a corresponding RAM location, and then clear the pre-counter. Accordingly, the pre-counters merely have to be wide enough such that even at a maximal event rate, the pre-counter will not be able to wrap (i.e., reach capacity or overflow) before the “sweeper” state machine accesses the pre-counter.

Abstract: A computer-implemented method, apparatus, and computer program product are disclosed for migrating data from a source physical page to a destination physical page. A migration process is begun to migrate data from the source physical page to the destination physical page which causes a host bridge to enter a first state. The host bridge then suspends processing of direct memory access operations when the host bridge is in the first state. The data is migrated from the source physical page to the destination physical page while the host bridge is in the first state.

Abstract: A credit-based flow control checking scheme is presented for controlling data communications in a closed loop system comprising a sender, a receiver and a link coupling the sender and receiver. The credit-based scheme includes automatically periodically transmitting a credit query from the receiver to the sender and upon return receipt of a credit acknowledge containing the available credit count maintained by the sender, determining whether credit gain or credit loss has occurred subsequent to initialization of the closed loop system. Along with automatically determining whether credit gain or credit loss has occurred, a method/system is presented for automatically correcting the loss or gain without requiring resetting of the closed loop system.

Abstract: A credit-based flow control checking scheme is presented for controlling data communications in a closed loop system comprising a sender, a receiver and a link coupling the sender and receiver. The credit-based scheme includes automatically periodically transmitting a credit query from the receiver to the sender and upon return receipt of a credit acknowledge containing the available credit count maintained by the sender, determining whether credit gain or credit loss has occurred subsequent to initialization of the closed loop system. Along with automatically determining whether credit gain or credit loss has occurred, a method/system is presented for automatically correcting the loss or gain without requiring resetting of the closed loop system.